Harry B. Bingham - DTU Orbit (17/05/14) Harry B. Bingham Home addressSchlegels Alle 3,st tv1807, Frederiksberg CDenmark

Department of Mechanical Engineering

Nils Koppels All, 403, 005

2800, Kgs. Lyngby

Denmark

hbb@mek.dtu.dk

http://www.web.mek.dtu.dk/staff/hbb/

Phone: 45251972

Job title:Associate Professor

Fluid Mechanics, Coastal and Maritime Engineering

Department of Informatics and Mathematical Modeling

04/07/03 to 15/05/14

305, 116

Denmark

hbb@imm.dtu.dk

http://www.imm.dtu.dk/~hbb

Phone: 45253080

Fax: 45932373

Job title:Forskningslektor

Maritime Engineering

30/11/12 to 30/11/12

Coastal, Maritime and Structural Engineering

25/02/12 to 10/05/12

Publications:

An efficient domain decomposition strategy for wave loads on surface piercing circular cylindersA fully nonlinear domain decomposed solver is proposed for efficient computations of wave loads on surface piercingstructures in the time domain. A fully nonlinear potential flow solver was combined with a fully nonlinearNavierStokes/VOF solver via generalized coupling zones of arbitrary shape. Sensitivity tests of the extent of the innerNavierStokes/VOF domain were carried out. Numerical computations of wave loads on surface piercing circular cylindersat intermediate water depths are presented. Four different test cases of increasing complexity were considered; 1) weaklynonlinear regular waves on a sloping bed, 2) phase-focused irregular waves on a flat bed, 3) irregular waves on a slopingbed and 4) multidirectional irregular waves on a sloping bed. For all cases, the free surface elevation and the inline forcewere successfully compared against experimental measurements. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Departmentof Wind Energy, Fluid Mechanics

Authors:Paulsen, B. T. (Intern), Bredmose, H. (Intern), Bingham, H. B. (Intern)Keywords: (Domain decomposition, Computational fluid dynamics, Potential flow, Free surface flows, Wave loads oncircular cylinders, Multi-directional waves)Pages:57-76Publication date:2014Main Research Area:Technical/natural sciences Publication informationJournal:Coastal EngineeringVolume:86ISSN (Print):0378-3839Ratings:FI (2012): 2 ISI indexed (2012): yes FI (2011): 2 ISI indexed (2011): yes FI (2010): 2 FI (2009): 2 FI (2008): 2 Original language:EnglishDOIs:10.1016/j.coastaleng.2014.01.006 Source:dtuSource-ID:n::oai:DTIC-ART:elsevier/434618931::38065Publication: Research - peer-review Journal article Annual report year: 2014

A non-linear wave decomposition model for efficient wavestructure interaction. Part A: Formulation, validations andanalysisThis paper deals with the development of an enhanced model for solving wavewave and wavestructure interactionproblems. We describe the application of a non-linear splitting method originally suggested by Di Mascio et al. [1], to thehigh-order finite difference model developed by Bingham et al. [2] and extended by Engsig-Karup et al. [3] and [4]. Theenhanced strategy is based on splitting all solution variables into incident and scattered fields, where the incident field isassumed to be known and only the scattered field needs to be computed by the numerical model. Although this splittingtechnique has been applied to both potential flow and NavierStokes solvers in the past, it has not been thoroughlydescribed and analyzed, nor has it been presented in widely read journals. Here we describe the method in detail andcarefully analyze its performance using several 2D linear and non-linear test cases. In particular, we consider the extremecase of non-linear waves up to the point of breaking reflecting from a vertical wall; and conclude that no limitations areimposed by adopting this splitting. The advantages of this strategy in terms of robustness, accuracy and efficiency are alsodemonstrated by comparison with the more common strategy of solving the incident and scattered fields together. General informationState:PublishedOrganisations:Department of Applied Mathematics and Computer Science , Scientific Computing, Department ofMechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, L'Universit Nantes Angers Le MansAuthors:Ducrozet, G. (Intern), Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern), Ferrant, P. (Ekstern)Keywords: (High-order finite differences, OceanWave3D, Wavestructure interaction, Non-linear decomposition,Standing waves, Offshore engineering)Pages:863883Publication date:2014Main Research Area:Technical/natural sciences Publication informationJournal:Journal of Computational PhysicsVolume:257ISSN (Print):0021-9991Ratings:FI (2012): 1 ISI indexed (2012): yes FI (2011): 1 ISI indexed (2011): yes FI (2010): 1

FI (2009): 1 FI (2008): 1 Original language:EnglishDOIs:10.1016/j.jcp.2013.09.017 Source:dtuSource-ID:u::9549Publication: Research - peer-review Journal article Annual report year: 2014

Corrigendum to Second-order theory for coupling 2D numerical and physical wave tanks-Derivation, evaluation andexperimental validation [Coast. Eng. 71 (2013) 3751] General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, State KeyLaboratory of Coastal and Offshore Engineering, Dalian University of TechnologyAuthors:Yang, Z. (Ekstern), Liu, S. (Ekstern), Bingham, H. B. (Intern), Li, J. (Ekstern)Pages:87-88Publication date:2014Main Research Area:Technical/natural sciences Publication informationJournal:Coastal EngineeringVolume:85ISSN (Print):03783839Ratings:FI (2012): 2 ISI indexed (2012): yes FI (2011): 2 ISI indexed (2011): yes FI (2010): 2 FI (2009): 2 FI (2008): 2 Original language:EnglishDOIs:10.1016/j.coastaleng.2013.12.004 Source:dtuSource-ID:n::oai:DTIC-ART:elsevier/430126847::37170Publication: Research - peer-review Journal article Annual report year: 2014

A note on added resistance for slow ships General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Bingham, H. B. (Intern), Amini Afshar, M. (Intern)Number of pages:4Publication date:2013 Publication informationDocuments:A_note_on_added_resistance_for_slow_ships.pdf Bibliographical noteThe authors wish to thank the EU 7th Framework Programme (grant # 266030, ULYSSES) for funding, and the DanishCenter for Scientific Computing for supercomputing resources.Main Research Area:Technical/natural sciencesSource:dtuSource-ID:u::7047

Publication: Research Working paper Annual report year: 2013

Effects from fully nonlinear irregular wave forcing on the fatigue life of an offshore wind turbine and its monopile foundationThe effect from fully nonlinear irregular wave forcing on the fatigue life of the foundation and tower of an offshore windturbine is investigated through aeroelastic calculations. Five representative sea states with increasing significant waveheight are considered in a water depth of 40 m. The waves are both linear and fully nonlinear irregular 2D waves. Thewind turbine is the NREL 5-MW reference wind turbine. Fatigue analysis is performed in relation to analysis of thesectional forces in the tower and monopile. Impulsive excitation of the sectional force at the bottom of the tower is seen when the waves are large and nonlinear andmost notably for small wind speeds. In case of strong velocities and turbulent wind, the excitation is damped out. In themonopile no excitation of the force is seen, but even for turbulent strong wind the wave affects the forces in the pilesignificantly. The analysis indicates that the nonlinearity of the waves can change the fatigue damage level significantly inparticular when the wave and wind direction is misaligned. General informationState:PublishedOrganisations:Department of Wind Energy, Fluid Mechanics, Aeroelastic Design, Department of Mechanical Engineering,Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Schler, S. (Intern), Bredmose, H. (Intern), Bingham, H. B. (Intern), Larsen, T. J. (Intern)Pages:393-402Publication date:2013 Host publication informationTitle:Proceedings of the ASME 31th 2012 International Conference on Ocean, Offshore and Arctic EngineeringVolume:7Publisher:American Society of Mechanical EngineersChapter:OMAE2012-83477BFI conference series:International Conference on Ocean, Offshore and Arctic Engineering (5010067)Main Research Area:Technical/natural sciencesConference:31st ASME International Conference on Ocean, Offshore and Arctic Engineering, Rio de Janeiro, Brazil,01/07/12 - 01/07/12Source:dtuSource-ID:u::5920Publication: Research - peer-review Article in proceedings Annual report year: 2012

Efficient computations of wave loads on offshore structuresThe present thesis considers numerical computations of fully nonlinear wave impacts on bottom mounted surface piercingcircular cylinders at intermediate water depths. The aim of the thesis is to provide new knowledge regarding wave loadson foundations for offshore wind turbines. Hence, the dimensions of the cylinders and the chosen wave parameters wereinspired by typical monopile foundations for offshore wind turbines. The numerical computations are carried out using three numerical solvers. That is, the fully nonlinear Navier-Stokes/VOFsolver provided as a part of the open-source CFD-toolbox OpenFoam R, the fully nonlinear potential flow solverOceanWave3D and finally a fully nonlinear domain decomposed solver, which was developed as part of this project. In thedomain decomposed solver, the outer wave field is described by the potential flow solver, whereas the inner wave field, inthe vicinity of a given structure, is described by the Navier-Stokes/VOF solver. All numerical models are carefully validated either in terms of convergence by grid refinement or by comparisons toexperimental measurements. Special attention is paid to the newly developed domain decomposed solver, which iscarefully validated against experimental measurements of regular-, irregular- and multi-directional irregular waves. Theability of the numerical model to accurately reproduce experiments is also investigated. Wave impacts on a bottom mounted circular cylinder from steep regular waves are presented. Here, the inline forces andthe motion of the free surface is described as a function of the non-dimensional wave steepness, the relative water depth,the relative cylinder diameter and a co-existing current. From the computations, higher harmonic forces are determinedand compared against the Morison equation and established analytical force formulations accurate to the third order inwave steepness. The physics related to the strongly nonlinear load phenomena secondary load cycles is described and an explanation ofthe wave load phenomena is provided. To further support the explanation a simple inviscid kinematic model flow isderived. The discussion of wave impacts on circular cylinders is further extended to uni- and bi-directional phase-focused waves.Here, the influence of the nondimensional wave steepness and wave directionality is discussed. For the steepest waveimpacts secondary load cycles are observed and the physics of the impact and the mechanisms related to thesecondary load cycle are discussed and compared to the observations made for regular waves. Additionally, attention is paid to experimental determination of hydrodynamic forces. Significant differences between

experimentally measured and computed higher harmonic forces are observed and the differences are explained in termsof the eigenmotion of the test setup. Finally, the application of the domain decomposed solver is discussed in anengineering context. Here, a simple and robust way of identifying forces, which may be inaccuvii rately estimated by theMorison equation, is presented. It is suggested that these impacts are recomputed by the domain decomposed solver. General informationState:PublishedOrganisations:Fluid Mechanics, Coastal and Maritime Engineering, Department of Wind Energy, Fluid Mechanics,Department of Mechanical EngineeringAuthors:Paulsen, B. T. (Intern), Bingham, H. B. (Intern), Bredmose, H. (Intern)Number of pages:132Publication date:2013 Publication informationPlace of publication:Kgs. LyngbyPublisher:Technical University of DenmarkOriginal language:EnglishMain Research Area:Technical/natural sciencesDocuments:Ph.D._Thesis_Bo_Terp_Paulsen..PDF RelationsProjects:Efficient computations of wave loads on offshore structures Publication: Research Ph.D. thesis Annual report year: 2013

Efficient Hybrid-Spectral Model for Fully Nonlinear Numerical Wave TankA new hybrid-spectral solution strategy is proposed for the simulation of the fully nonlinear free surface equations basedon potential flow theory. A Fourier collocation method is adopted horisontally for the discretization of the free surfaceequations. This is combined with a modal Chebyshev Tau method in the vertical for the discretization of the Laplaceequation in the fluid domain, which yields a sparse and spectrally accurate Dirichletto-Neumann operator. The Laplaceproblem is solved with an efficient Defect Correction method preconditioned with a spectral discretization of the linearisedwave problem, ensuring fast convergence and optimal scaling with the problem size. Preliminary results for very nonlinearwaves show expected convergence rates and a clear advantage of using spectral schemes. General informationState:PublishedOrganisations:Department of Applied Mathematics and Computer Science , Scientific Computing, Department ofMechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Ecole Centrale de NantesAuthors:Christiansen, T. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Ducrozet, G. (Ekstern), Ferrant, P.(Ekstern)Number of pages:10Publication date:2013 Host publication informationTitle:32nd International Conference on Ocean, Offshore and Arctic EngineeringVolume:9Publisher:American Society of Mechanical EngineersArticle number:OMAE2013-10861ISBN (Print):978-0-7918-5543-0BFI conference series:International Conference on Ocean, Offshore and Arctic Engineering (5010067)Main Research Area:Technical/natural sciencesConference:32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), Nantes, France,09/06/13 - 09/06/13DOIs:10.1115/OMAE2013-10861 Source:FindItSource-ID:262007271Publication: Research - peer-review Article in proceedings Annual report year: 2014

Hybrid-Spectral Model for Fully Nonlinear Numerical Wave Tank General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Departmentof Applied Mathematics and Computer Science , Scientific ComputingAuthors:Christiansen, T. R. B. (Intern), Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern)Number of pages:3Pages:37-40Publication date:2013 Host publication informationTitle:Proceedings of the 28th International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:28th International Workshop on Water Waves and Floating Bodies (IWWWFB 2013), Marseille, France,07/04/13 - 07/04/13Documents:iwwwfb28_10.pdf Source:dtuSource-ID:u::8562Publication: Research - peer-review Conference abstract in proceedings Annual report year: 2013

Loads and response from steep and breaking waves on monopiles General informationState:PublishedOrganisations:Department of Wind Energy, Fluid Mechanics, Aeroelastic Design, Department of Mechanical Engineering,Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Bredmose, H. (Intern), Schler, S. (Intern), Sahlberg-Nielsen, L. (Ekstern), Slabiak, P. (Ekstern), Larsen, T. J.(Intern), Kim, T. (Ekstern), Paulsen, B. T. (Intern), Bingham, H. B. (Intern), Jacobsen, N. G. (Intern), Tornfeldt Srensen, J.(Ekstern), Schltter, F. (Ekstern), Nielsen, A. W. (Intern)Number of pages:48Publication date:2013 Publication informationMedia of output:PowerPointOriginal language:EnglishMain Research Area:Technical/natural sciencesDocuments:Loads_and_responses_from_steep_and_breaking_waves_Henrik_Bredmose.pdf Publication: Research Sound/Visual production (digital) Annual report year: 2013

Multiscale Simulation of Breaking Wave ImpactsThe purpose of this project is to make an accurate, robust, geometric flexible and efficient model for calculation of forceson structures from nonlinear ocean waves and breaking wave impacts. Accurate prediction of the extreme forces on windturbine foundations, breakwaters and tidal or wave power devises are important for enhancement structural designs. The proposed model is based on an incompressible and inviscid flow approximation and the governing equations areapplied in an arbitrary Lagrangian-Eulerian moving frame of reference (ALE). The Runge-Kutta method (RK) is used fortime integration and mass conservation is satisfied through a pressure-corrector type calculation of the pressure. Theweighted least squares method (WLS) is combined with approximate Riemann solvers to introduce numerical smoothingof the solution around steep gradients in the velocity and pressure fields. The Poisson equation is solved and the pressureboundary conditions are satisfied by a generalized finite pointset method (GFPM); This provides a geometrically flexibleand stable solution for the fluid pressure. The numerical approximations of these equations are performed on unstructuredpoint distributions and the solutions for velocity and pressure are represented by WLS approximation of multivariatepolynomials. The stencils for the ALE-WLS and GFPM methods are found through a breadth first search (BFS) in amodified Delaunay graph. This graph is the discrete representation of the fluid domain and the connectivity between thecalculation points. The graph is updated according to the evolving topology of the fluid domain caused by the fluidreaching or leaving a solid boundary or the free surface colliding with itself or another free-surface. After each time stepthe fluid domain is checked for any of these intersections and the topology is updated accordingly in its graphrepresentation. The calculation points move in a Lagrangian way and this can cause ill-conditioning of the generalizedVandermonde matrix in the WLS and GFPM methods. To prevent this the point set is refined and coarsened by a fill-distance based adaptivity method and redistributed via a point position filtering method. The incompressible and inviscid

ALE-WLS model is applied to the following standard validation test cases: deforming elliptical drop, small amplitudestanding waves and the dam break problem. The deforming elliptical drop test show that the model can calculate thekinematics and dynamics of this free surface flow accurately and robustly. The small amplitude standing wave gives thesame conclusions. Long time integration of this small amplitude periodic motion is possible due to accurate free surfaceevolution and small errors in the fluid volume. The dam break test case shows that the incompressible and inviscid ALE-WLS model can calculate nonlinear fluid motion, fluid structure impacts and overturning waves. The propagation speed ofthe wetting front and impact pressures are compared to experiments and the results compare reasonably well. Theincompressible and inviscid ALE-WLS model is coupled with the potential flow model of Engsig-Karup et al. [2009], toperform multiscale calculation of breaking wave impacts on a vertical breakwater. The potential flow model providesaccurate calculation of the wave transformation from offshore to the vicinity of the breakwater. The wave breaking close tothe breakwater and the wave impact are calculated by the incompressible ALE-WLS model. The forces calculated with theincompressible and inviscid ALE-WLS model are 1 - 2 times the corresponding compressible calculations in Bredmose etal. [2009] for the calculations without trapped air. Among the contributions of this project are the ALE-WLS method combined with approximate Riemann solvers and thegeneralization of the FPM method to arbitrary order of accuracy. The WLS and GFPM stencils found using the BFS datastructure, which is updated due to topology changes of the evolving fluid domain. This extension combined with ALE-WLSand approximate Riemann solvers gives a numerical model capable of calculation of forces due to breaking wave impacts.The incompressible and inviscid ALE-WLS model has been coupled with a potential flow model to provide multiscalecalculation of forces from breaking wave impacts on structures. General informationState:PublishedOrganisations:Department of Mechanical EngineeringAuthors:Lindberg, O. (Intern), Engsig-Karup, A. P. (Intern), Walther, J. H. (Intern), Bingham, H. B. (Intern)Number of pages:125Publication date:2013 Publication informationPlace of publication:Kgs. LyngbyPublisher:Technical University of DenmarkOriginal language:EnglishMain Research Area:Technical/natural sciencesDocuments:PhD_thesis_Ole_Lindberg.pdf RelationsProjects:Multiscale Simulation of Breaking Wave Impacts Publication: Research Ph.D. thesis Annual report year: 2013

Real-Time Simulation of Ship-Structure and Ship-Ship InteractionThis paper gives the status of the development of a ship-hydrodynamic model for real-time ship-wave calculation and ship-structure and ship-ship interaction in a full mission marine simulator. The hydrodynamic model is based on potential flowtheory, linear or non-linear free surface boundary condition and higher-order accurate numerical approximations. Theequations presented facilitate both Neumann-Kelvin and double-body linearizations. The body boundary condition on theship hull is approximated by a static and dynamic moving pressure distribution. The pressure distribution method is used,because it is simple, easy to implement and computationally efficient. Multiple many-core graphical processing units(GPUs) are used for parallel execution and the model is implemented using a combination of C/C++, CUDA and MPI. Twoship hydrodynamic cases are presented: Kriso Container Carrier at steady forward speed and lock entrance of a TEU12.000 Container Carrier. These calculations reveal that the pressure distribution model is a too simple approximation ofthe body boundary condition and that it has the limitations of a flat-ship approximation. It is necessary to investigate moreaccurate approximations of the body boundary condition, which does not compromise the overall computational efficiency. General informationState:PublishedOrganisations:Department of Applied Mathematics and Computer Science , Scientific Computing, Department ofMechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, FORCE TechnologyAuthors:Lindberg, O. (Intern), Glimberg, S. L. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Schjeldahl, P.J. (Ekstern)Number of pages:8Publication date:2013 Host publication informationTitle:Proceedings of the 3rd International Conference on Ship Manoeuvring in Shallow and Confined Water 2013

Main Research Area:Technical/natural sciencesConference:3rd International Conference on Ship Manoeuvring in Shallow and Confined Water, Ghent, Belgium, 03/06/13- 03/06/13Source:dtuSource-ID:u::8564Publication: Research - peer-review Article in proceedings Annual report year: 2013

Second-order theory for coupling 2D numerical and physical wave tanks: Derivation, evaluation and experimentalvalidationA full second-order theory for coupling numerical and physical wave tanks is presented. The ad hoc unified wavegeneration approach developed by Zhang et al. [Zhang, H., Schffer, H.A., Jakobsen, K.P., 2007. Deterministiccombination of numerical and physical coastal wave models. Coast. Eng. 54, 171186] is extended to include the second-order dispersive correction. The new formulation is presented in a unified form that includes both progressive andevanescent modes and covers wavemaker configurations of the piston- and flap-type. The second order paddle strokecorrection allows for improved nonlinear wave generation in the physical wave tank based on target numerical solutions.The performance and efficiency of the new model is first evaluated theoretically based on second order Stokes waves.Due to the complexity of the problem, the proposed method has been truncated at 2D and the treatment of regular waves,and the re-reflection control on the wave paddle is also not included. In order to validate the solution methodology further,a series of nonlinear, periodic waves based on stream function theory are generated in a physical wave tank using apiston-type wavemaker. These experiments show that the new second-order coupling theory provides an improvement inthe quality of nonlinear wave generation when compared to existing techniques. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, State KeyLaboratory of Coastal and Offshore Engineering, Dalian University of TechnologyAuthors:Yang, Z. (Ekstern), Liu, S. (Ekstern), Bingham, H. B. (Intern), Li, J. (Ekstern)Keywords: (Second-order coupling, Numerical wave tanks, Physical wave tanks, Wavemaker theory)Pages:37-51Publication date:2013Main Research Area:Technical/natural sciences Publication informationJournal:Coastal EngineeringVolume:71ISSN (Print):0378-3839Ratings:FI (2012): 2 ISI indexed (2012): yes FI (2011): 2 ISI indexed (2011): yes FI (2010): 2 FI (2009): 2 FI (2008): 2 Original language:EnglishDocuments:dlib.dtu.pdf DOIs:10.1016/j.coastaleng.2012.07.003 Source:dtuSource-ID:n::oai:DTIC-ART:elsevier/370287357::19794Publication: Research - peer-review Journal article Annual report year: 2013

Steep wave loads from irregular waves on an offshore wind turbine foundation: Computation and experimentTwo-dimensional irregular waves on a sloping bed and their impact on a bottom mounted circular cylinder is modeled bythree different numerical methods and the results are validated against laboratory experiments. We here consider theperformance of a linear-, a fully nonlinear potential flow solver and a fully nonlinear Navier-Stokes/VOF solver. Thevalidation is carried out in terms of both the free surface elevation and the inline force. Special attention is paid to theultimate load in case of a single wave event and the general ability of the numerical models to capture the higher harmonicforcing. The test case is representative for monopile foundations at intermediate water depths. The potential flow

computations are carried out in a two-dimensional vertical plane and the inline force on the cylinder is evaluated by theMorison equation. The Navier-Stokes/VOF computations are carried out in three-dimensions and the force is obtained byspatial pressure integration over the wettet area of the cylinder. In terms of both the free surface elevation and inline force,the linear potential flow model is shown to be of limited accuracy and large deviations are generally seen when comparedto the experimental measurements. The fully nonlinear Navier-Stokes/VOF computations are accurately predicting boththe free surface elevation and the inline force. However, the computational cost is high relative to the potential flowsolvers. Despite the fact that the nonlinear potential flow model is carried out in two-dimensions it is shown to perform justas good as the three-dimensional Navier-Stokes/VOF solver. This is observed for both the free surface elevation and theinline force, where both the ultimate load and the higher harmonic forces are accurately predicted. This shows that formoderately steep irregular waves a Morison equation combined with a fully nonlinear two-dimensional potential flow solvercan be a good approximation. General informationState:PublishedOrganisations:Fluid Mechanics, Coastal and Maritime Engineering, Department of Mechanical Engineering, Departmentof Wind Energy, Fluid MechanicsAuthors:Paulsen, B. T. (Intern), Bingham, H. B. (Intern), Bredmose, H. (Intern), Schler, S. (Intern)Number of pages:10Publication date:2013 Host publication informationTitle:Proceedings of ASME 2013 32st International Conference on Ocean, Offshore and Arctic EngineeringVolume:9Publisher:American Society of Mechanical EngineersArticle number:OMAE2013-10727Main Research Area:Technical/natural sciencesConference:32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), Nantes, France,09/06/13 - 09/06/13Source:dtuSource-ID:u::9799Publication: Research - peer-review Article in proceedings Annual report year: 2013

The second-order decomposition model of nonlinear irregular wavesA new method to decompose the nonlinear irregular waves is proposed. The second-order potential flow theory isemployed to construct the relation of the second-order items solution by deriving the transfer function between the first-and the second-order components. Target waves are decomposed into the first- and the second-order super-harmonic aswell as the second-order sub-harmonic components by transferring them into an identical Fourier frequency-space andusing a Newton-Raphson iteration method. In order to evaluate the present model, a variety of monochromatic waves andthe second-order nonlinear irregular waves over a broad range of frequencies have been analyzed, and the effects onwave nonlinearity are analyzed. The experimental results show that the present method is reasonably effective for thewave decomposition. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, DalianUniversity of TechnologyAuthors:Yang, Z. W. (Ekstern), Bingham, H. B. (Intern), Li, J. X. (Ekstern), Liu, S. X. (Ekstern)Keywords: (Newton-Raphson iteration, Nonlinear irregular waves, The second-order decomposition)Number of pages:8Pages:871-878Publication date:2013Main Research Area:Technical/natural sciences Publication informationJournal:Dalian Ligong Daxue Xuebao (Shehui Kexue Ban)Volume:53Journal number:6ISSN (Print):1008-407XRatings:ISI indexed (2012): no ISI indexed (2011): no Original language:EnglishSource:FindItSource-ID:260124271

Publication: Research - peer-review Journal article Annual report year: 2014

Towards real time simulation of ship-ship interaction - Part II: double body flow linearization and GPU implementation General informationState:PublishedOrganisations:Department of Applied Mathematics and Computer Science , Scientific Computing, Department ofMechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, FORCE TechnologyAuthors:Lindberg, O. (Intern), Glimberg, S. L. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Schjeldahl, P.J. (Ekstern)Number of pages:4Pages:125-128Publication date:2013 Host publication informationTitle:Proceedings of the 28th International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:28th International Workshop on Water Waves and Floating Bodies (IWWWFB 2013), Marseille, France,07/04/13 - 07/04/13Documents:iwwwfb28_32.pdf Publication: Research - peer-review Conference abstract in proceedings Annual report year: 2013

Accurate computation of wave loads on a bottom fixed circular cylinderThis abstract describes recent progress in the development of a fast and accurate tool for computations of wave-structureinteractions of realistic sea states that include breaking waves. The practical motivation is extreme wave loads on offshore wind turbine foundations, but the tool is applicable to a rangeof other problems. The central idea is to drive an inner CFD model that resolves the flow around the structure with an outer wave model thatis based on potential flow theory. By letting the potential flow solver describe the waves in the outer flow domain and theNavier-Stokes solver describe the flow in the inner domain a fast and accurate description of wave loads on offshorestructures is obtained, even for breaking waves. Engsig-Karup et. al [1] have recently developed a fully nonlinear potential flow solver (OceanWave3D) to representpropagation and development of fully nonlinear three-dimensional water waves up to the point of breaking. The CFD solver is the open source CFD toolbox OpenFOAMR in combination with the newly developed waves2Foamutility, which in [5] has been successfully applied to calculations of free surface flows. The numerical solution is obtainedby solving the incompressible Navier-Stokes equations in combination with a surface tracking scheme. The CFD solverhas been thoroughly tested for stability and first order grid convergence has been shown for the propagation of stream function waves. Here we present results for the magnitudes, of the third-harmonic forces on a vertical circular cylinder from steep waves.This partly serves as a validation and further brings insight into third-harmonic wave loads on cylinders which are relevantfor ringing. Next, preliminary results for the coupled model are presented in terms of irregular waves propagation and theassociated forces on a cylinder. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Departmentof Wind Energy, Fluid MechanicsAuthors:Paulsen, B. T. (Intern), Bredmose, H. (Intern), Bingham, H. B. (Intern)Number of pages:4Publication date:2012 Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:IWWWFB27, Copenhagen, Denmark, 22/04/12 - 22/04/12Documents:iwwwfb27_35.pdf Publication: Research Article in proceedings Annual report year: 2012

A comparative study of two fast nonlinear free-surface water wave modelsThis paper presents a comparison in terms of accuracy and efficiency between two fully nonlinear potential flow solvers forthe solution of gravity wave propagation. One model is based on the high-order spectral (HOS) method, whereas thesecond model is the high-order finite difference model OceanWave3D. Although both models solve the nonlinear potentialflow problem, they make use of two different approaches. The HOS model uses a modal expansion in the vertical directionto collapse the numerical solution to the two-dimensional horizontal plane. On the other hand, the finite difference modelsimply directly solves the three-dimensional problem. Both models have been well validated on standard test cases andshown to exhibit attractive convergence properties and an optimal scaling of the computational effort with increasingproblem size. These two models are compared for solution of a typical problem: propagation of highly nonlinear periodicwaves on a finite constant-depth domain. The HOS model is found to be more efficient than OceanWave3D with adifference dependent on the level of accuracy needed as well as the wave steepness. Also, the higher the order of thefinite difference schemes used in OceanWave3D, the closer the results come to the HOS model. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, ScientificComputing, Department of Informatics and Mathematical Modeling, Laboratoire de Mchanique des Fluides, EcoleCentrale NantesAuthors:Ducrozet, G. (Ekstern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Bonnefoy, F. (Ekstern), Ferrant, P.(Ekstern)Keywords: (Ocean-wave3D, Hydrodynamics, Water waves, High-order finite differences, High-order spectral, Numericalcomparisons)Pages:1818-1834Publication date:2012Main Research Area:Technical/natural sciences Publication informationJournal:International Journal for Numerical Methods in FluidsVolume:69ISSN (Print):0271-2091Ratings:FI (2012): 1 ISI indexed (2012): yes FI (2011): 1 ISI indexed (2011): yes FI (2010): 1 FI (2009): 1 FI (2008): 1 Original language:EnglishDOIs:10.1002/fld.2672 Source:orbitSource-ID:276225Publication: Research - peer-review Journal article Annual report year: 2011

A Comparison of Methods for Computing the Added Resistance General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, FORCETechnologyAuthors:Joncquez, S. (Ekstern), Andersen, P. (Intern), Bingham, H. B. (Intern)Keywords: (Seakeeping, Waves)Pages:106-119Publication date:2012Main Research Area:Technical/natural sciences Publication informationJournal:Journal of Ship ResearchVolume:56Journal number:2ISSN (Print):0022-4502

Ratings:FI (2012): 1 ISI indexed (2012): yes FI (2011): 1 ISI indexed (2011): yes FI (2010): 1 FI (2009): 1 FI (2008): 1 Original language:EnglishDOIs:10.5957/JOSR.56.2.100003 Source:dtuSource-ID:n::oai:DTIC-ART:swets/365412217::17667Publication: Research - peer-review Journal article Annual report year: 2012

A Coupled Finite Difference and Moving Least Squares Simulation of Violent Breaking Wave ImpactTwo model for simulation of free surface flow is presented. The first model is a finite difference based potential flow modelwith non-linear kinematic and dynamic free surface boundary conditions. The second model is a weighted least squaresbased incompressible and inviscid flow model. A special feature of this model is a generalized finite point set methodwhich is applied to the solution of the Poisson equation on an unstructured point distribution. The presented finite point setmethod is generalized to arbitrary order of approximation. The two models are applied to simulation of steep andoverturning wave impacts on a vertical breakwater. Wave groups with five different wave heights are propagated fromoffshore to the vicinity of the breakwater, where the waves are steep, but still smooth and non-overturning. These wavesare used as initial condition for the weighted least squares based incompressible and inviscid model and the wave impactson the vertical breakwater are simulated in this model. The resulting maximum pressures and forces on the breakwaterare relatively high when compared with other studies and this is due to the incompressible nature of the present model. General informationState:PublishedOrganisations:Fluid Mechanics, Coastal and Maritime Engineering, Department of Mechanical Engineering, Departmentof Informatics and Mathematical Modeling, Scientific ComputingAuthors:Lindberg, O. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern)Number of pages:12Publication date:2012 Host publication informationTitle:Proceedings of 31st International Conference on Ocean, Offshore and Arctic EngineeringPublisher:American Society of Mechanical EngineersBFI conference series:International Conference on Ocean, Offshore and Arctic Engineering (5010067)Main Research Area:Technical/natural sciencesConference:31st ASME International Conference on Ocean, Offshore and Arctic Engineering, Rio de Janeiro, Brazil,01/07/12 - 01/07/12Source:dtuSource-ID:u::6058Publication: Research - peer-review Article in proceedings Annual report year: 2012

A High-Order WENO Finite Difference Water Wave Model for Interactive Ship-Wave Simulation General informationState:PublishedOrganisations:Department of Informatics and Mathematical Modeling, Scientific Computing, Department of MechanicalEngineering, Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Engsig-Karup, A. P. (Intern), Lindberg, O. (Intern), Glimberg, S. L. (Intern), Dammann, B. (Intern), Bingham, H. B.(Intern), Madsen, P. A. (Intern)Number of pages:2Publication date:2012Event:Paper presented at International Conference on Spectral and High Order Methods (ICOSAHOM 2012), Gammarth,Tunisia.Main Research Area:Technical/natural sciencesSource:dtu

Source-ID:u::6062Publication: Research - peer-review Paper Annual report year: 2012

An ALE Weighted Least Squares Method for Simulation of Violent Water Wave Impact General informationState:PublishedOrganisations:Fluid Mechanics, Coastal and Maritime Engineering, Department of Mechanical Engineering, Departmentof Informatics and Mathematical Modeling, Scientific ComputingAuthors:Lindberg, O. (Intern), Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern)Number of pages:2Publication date:2012Event:Paper presented at International Conference on Spectral and High Order Methods (ICOSAHOM 2012), Gammarth,Tunisia.Main Research Area:Technical/natural sciencesSource:dtuSource-ID:u::6060Publication: Research - peer-review Paper Annual report year: 2012

An overset grid approach to linear wave-structure interactionA finite-difference based approach to wave-structure interaction is reported that employs the overset approach to gridgeneration. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiationproblem for a floating body of arbitrary form. This software implementation has been validated by performing time-domainsimulations to evaluate the dynamic forces applied to a half-submerged cylinder and a rectangular barge in response to aprescribed motion. A Gaussian displacement is used to introduce a range of wave frequencies, thereby allowing themeasurement of the body response over the frequency range of interest. The radiation addedmass and dampingcoefficients of both bodies have been evaluated and compared to exact analytical solutions. The numerical and analytical results show good agreement when the modesof excitation and response are the same. The cross-coupled results are in qualitative agreement, but show somequantitative variations that may be related to slight differences in the fluid domain geometry. For both the cylinder and thebarge, the effects of bottom slope on the coefficients are found to be minimal. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Read, R. (Intern), Bingham, H. B. (Intern)Keywords: (OMAE2012-83568)Number of pages:10Publication date:2012 Host publication informationTitle:Proceedings of the ASME 2012 31st International Conference on Ocean, Offshore and Arctic EngineeringPublisher:American Society of Mechanical EngineersBFI conference series:International Conference on Ocean, Offshore and Arctic Engineering (5010067)Main Research Area:Technical/natural sciencesConference:31st ASME International Conference on Ocean, Offshore and Arctic Engineering, Rio de Janeiro, Brazil,01/07/12 - 01/07/12Source:dtuSource-ID:u::7052Publication: Research - peer-review Article in proceedings Annual report year: 2012

Efficient Pseudo-Spectral Model for Free Surface Nonlinear Water Waves General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Departmentof Informatics and Mathematical Modeling, Scientific Computing, Ecole Centrale de Nantes - LHEEA Lab.Authors:Christiansen, T. R. B. (Intern), Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern), Ducrozet, G. (Intern),Ferrant, P. (Ekstern)

Number of pages:2Publication date:2012Event:Paper presented at International Conference on Spectral and High Order Methods (ICOSAHOM 2012), Gammarth,Tunisia.Main Research Area:Technical/natural sciencesSource:dtuSource-ID:u::6061Publication: Research - peer-review Paper Annual report year: 2012

Efficient psudo-spectral model for nonlinear water waves General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Departmentof Informatics and Mathematical Modeling, Scientific ComputingAuthors:Christiansen, T. (Ekstern), Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern)Publication date:2012 Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:IWWWFB27, Copenhagen, Denmark, 22/04/12 - 22/04/12Publication: Research Article in proceedings Annual report year: 2012

High-order Finite Difference Solution of Euler Equations for Nonlinear Water WavesThe incompressible Euler equations are solved with a free surface, the position of which is captured by applying anEulerian kinematic boundary condition. The solution strategy follows that of [1, 2], applying a coordinate-transformation toobtain a time-constant spatial computational domain which is discretized using arbitrary-order finite difference schemes ona staggered grid with one optional stretching in each coordinate direction. The momentum equations and kinematic freesurface condition are integrated in time using the classic fourth-order Runge-Kutta scheme. Mass conservation is satisfiedimplicitly, at the end of each time stage, by constructing the pressure from a discrete Poisson equation, derived from thediscrete continuity and momentum equations and taking the time-dependent physical domain into account. An efficientpreconditionedDefect Correction (DC) solution of the discrete Poisson equation for the pressure is presented, in which thepreconditioning step is based on an order-multigrid formulation with a direct solution on the lowest order-level. Thisensures fast convergence of the DC method with a computational effort which scales linearly with the problem size.Results obtained with a two-dimensional implementation of the model are compared with highly accurate stream functionsolutions to the nonlinear wave problem, which show the approximately expected convergence rates and a clearadvantage of using high-order finite difference schemes in combination with the Euler equations. General informationState:PublishedOrganisations:Department of Informatics and Mathematical Modeling, Scientific Computing, Department of MechanicalEngineering, Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Christiansen, T. R. B. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern)Number of pages:10Publication date:2012 Host publication informationTitle:Proceedings of the ASME 2012 31st International Conference on Ocean, Offshore and ArcticPublisher:American Society of Mechanical EngineersBFI conference series:International Conference on Ocean, Offshore and Arctic Engineering (5010067)Main Research Area:Technical/natural sciencesConference:31st ASME International Conference on Ocean, Offshore and Arctic Engineering, Rio de Janeiro, Brazil,01/07/12 - 01/07/12Source:dtuSource-ID:u::6059Publication: Research - peer-review Article in proceedings Annual report year: 2012

Solving the linear radiation problem using a volume method on an overset gridThis paper describes recent progress towards the development of a computational tool, based on potential ow theory, that can accurately and effciently simulate wave-induced loadings on marine structures. Engsig-Karup et al.(2009) have successfully developed an arbitrary-order, finite-differencebased, potentialow model to represent thepropagation of fully non-linear waves in coastal regions of varying bathymetry. The present objective is to develop thismethodology to include the presence of a oating structure. To represent the curvilinear boundaries of the structure and thebottom, the single-block methodology developed previously is applied to multiple, overlapping grid blocks using the overset approach. While the ultimate aim of this work is to model fully non-linear wave-structure interaction, a linearsolver has been initially implemented to permit the use of a fixed grid, and to allow comparison of numerical results withestablished analytical solutions. The linear radiation problem is considered in this paper. A two-dimensional computational tool has been developed tocalculate the force applied to a floating body of arbitrary form in response to a prescribed displacement. Fourier transformsof the time-dependent displacement and force are applied, and the ratio of the resulting signals used to determine theradiation added mass and damping of the body as a function of frequency. The present software implementation has beenvalidated by comparing numerical results from the linear model with analytical solutions for several test cases. Thedynamic behaviour of a cylinder and barge on variable bathymetry has been investigated on a multi-block grid in two dimensions. Simulations have been performed to evaluate the induced flow field and radiationforces generated by these bodies in response to a Gaussian displacement. The hydrodynamic coecients associated withbody motions in surge, heave, and pitch have been calculated and compared with exact solutions. A three-dimensionalimplementation of the linear model has recently been completed. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime EngineeringAuthors:Read, R. (Intern), Bingham, H. B. (Intern)Number of pages:4Publication date:2012 Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:IWWWFB27, Copenhagen, Denmark, 22/04/12 - 22/04/12Documents:abstract_2012.pdf Source:dtuSource-ID:u::4064Publication: Research Article in proceedings Annual report year: 2012

Towards Real Time Simulation of Ship-Ship InteractionWe present recent and preliminary work directed towards the development of a simplified, physics-based model forimproved simulation of ship-ship interaction that can be used for both analysis and real-time computing (i.e. with real-timeconstraints due to visualization). The goal is to implement the model into a large maritime simulator for training of navalofficers, in particular tug boat helmsmen. Tug boat simulators are used for training of communication and situationawareness during manoeuvre involved with towing of large vessels. A main objective of the work is to improve and enablemore accurate (realistic) and much faster ship-wave and ship-ship simulations than are currently possible. The coupling ofsimulation with visualization should improve the visual experience such that it can be perceived as more realistic intraining. Today the state-of-art in real-time ship-ship interaction is for efficiency reasons and time-constraints in visualization based onmodel experiments in towing tanks and precomputed force tables. We anticipate that the fast, and highly parallel,algorithm described by Engsig-Karup et al. [2011] for execution on affordable modern high-throughput GraphicsProcessing Units (GPUs) can provide the basis for efficient simulations in combination with an accurate free-surface model for Ship-Ship simulation. Anotherarea of application is the determination of wave disturbances from a ship in a coastal environment, channels andharbours. The model proposed in the following can in a simple and efficient way calculate the wave field from a shipsailing in a finite depth sea, even with variations in the height of sea bed. The generated wave field can be applied as aninput to other models that simulate the marine environment on a larger scale. General informationState:PublishedOrganisations:Department of Mechanical Engineering, Fluid Mechanics, Coastal and Maritime Engineering, Departmentof Informatics and Mathematical Modeling, Scientific ComputingAuthors:Lindberg, O. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Madsen, P. A. (Intern)Number of pages:4Publication date:2012

Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:IWWWFB27, Copenhagen, Denmark, 22/04/12 - 22/04/12Documents:iwwwfb27_27.pdf Publication: Research Article in proceedings Annual report year: 2012

A coupled boundary element-finite difference solution of the elliptic modified mild slope equationThe modified mild slope equation of [5] is solved using a combination of the boundary element method (BEM) and thefinite difference method (FDM). The exterior domain of constant depth and infinite horizontal extent is solved by a BEMusing linear or quadratic elements. The interior domain with variable depth is solved by a flexible order of accuracy FDM inboundary-fitted curvilinear coordinates. The two solutions are matched along the common boundary of two methods (theBEM boundary) to ensure continuity of value and normal flux. Convergence of the individual methods is shown and thecombined solution is tested against several test cases. Results for refraction and diffraction of waves from submergedbottom mounted obstacles compare well with experimental measurements and other computed results from the literature. General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Department of CivilEngineering, Tehran UniversityAuthors:Naserizadeh, R. (Ekstern), Bingham, H. B. (Intern), Noorzad, A. (Ekstern)Keywords: (Modified mild slope equation, Wave amplification, Wave diffraction, Coupled boundary element-finitedifference method, Wave refraction)Pages:25-33Publication date:2011Main Research Area:Technical/natural sciences Publication informationJournal:Engineering Analysis with Boundary ElementsVolume:35Journal number:1ISSN (Print):0955-7997Ratings:FI (2012): 1 ISI indexed (2012): yes FI (2011): 1 ISI indexed (2011): yes FI (2010): 1 FI (2009): 1 FI (2008): 1 Original language:EnglishDOIs:10.1016/j.enganabound.2010.06.020 Source:orbitSource-ID:269206Publication: Research - peer-review Journal article Annual report year: 2011

High-order finite difference solution of the Euler equations for nonlinear waves General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Bingham, H. B. (Intern), Christiansen, T. R. B. (Intern)Publication date:2011 Host publication informationTitle:IWWWFB26Main Research Area:Technical/natural sciences

Workshop:26th International Workshop on Water Waves and Floating Bodies, Athens, Greece, 17/04/11 - 17/04/11Documents:iwwwfb26_03.pdf Bibliographical noteThe authors wish to thank the Danish Agency for Science, Technology and Innovation (grant # 09-067257) for funding,and the Danish Center for Scientific Computing for supercomputing resources.Source:orbitSource-ID:277388Publication: Research - peer-review Article in proceedings Annual report year: 2011

Irregular Wave Forces on Monopile Foundations. Effect af Full Nonlinearity and Bed SlopeForces on a monopile from a nonlinear irregular unidirectional wave model are investigated. Two seabed profiles ofdifferent slopes are considered. Morisons equation is used to investigate the forcing from fully nonlinear irregular wavesand to compare the results with those obtained from linear wave theory and with stream function wave theory. The latter ofthese theories is only valid on a flat bed. The three predictions of wave forces are compared and the influence of the bedslope is investigated. Force-profiles of two selected waves from the irregular wave train are further compared with thecorresponding forceprofiles from stream function theory. The results suggest that the nonlinear irregular waves give rise tolarger extreme wave forces than those predicted by linear theory and that a steeper bed slope increases the wave forcesboth for linear and nonlinear waves. It is further found that stream function theory in some cases underestimate the waveforces acting on the monopile. General informationState:PublishedOrganisations:Fluid Mechanics, Department of Mechanical Engineering, Coastal, Maritime and Structural EngineeringAuthors:Schler, S. (Intern), Bredmose, H. (Intern), Bingham, H. B. (Intern)Pages:581-588Publication date:2011 Host publication informationTitle:Proceedings of the ASME 30th 2011 International Conference on Ocean, Offshore and Arctic EngineeringVolume:5Publisher:American Society of Mechanical EngineersISBN (Print):9780791844373Main Research Area:Technical/natural sciencesConference:30th International Conference on Ocean, Offshore and Arctic Engineering, Rotterdam, Netherlands, 19/06/11- 19/06/11Documents:prod11321619361554.Paper[1].pdf Source:orbitSource-ID:312690Publication: Research - peer-review Article in proceedings Annual report year: 2011

Linear wave-structure interaction using overset grids General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Read, R. (Intern), Bingham, H. B. (Intern)Publication date:2011 Host publication informationTitle:IWWWFB26Main Research Area:Technical/natural sciencesWorkshop:26th International Workshop on Water Waves and Floating Bodies, Athens, Greece, 17/04/11 - 17/04/11Documents:iwwwfb26_38.pdf Bibliographical noteThe authors wish to thank the Danish Agency for Science, Technology and Innovation (grant The authors wish to thankthe Danish Agency for Science, Technology and Innovation (grantThe authors wish to thank the Danish Agency forScience, Technology and Innovation (grant The authors wish to thank the Danish Agency for Science, Technology and

Innovation (grant # 09-067257) for funding, and the Danish Center for Scientific Computing for supercomputing resources.Source:orbitSource-ID:277391Publication: Research - peer-review Article in proceedings Annual report year: 2011

Experimental and numerical study of the wave run-up along a vertical plateResults from experiments on wave interaction with a rigid vertical plate are reported. The 5m long plate is set against thewall of a 30m wide basin, at 100m from the wavemaker. This set-up is equivalent to a 10m plate in the middle of a 60mwide basin. Regular waves are produced, with wavelengths of 1.6m, 1.8m and 2m, and steepnesses H/L (H being thedouble amplitude and L being the wavelength) ranging from 2% to 5%. Free-surface elevations along the plate aremeasured with a row of 20 gauges. The focus is on the time evolution of the free-surface profile along the plate. At allsteepnesses, strong deviations from the predictions of linear theory gradually take place as the reflected wave fielddevelops in the basin. This phenomenon is attributed to third-order interactions between the incoming and reflected wavesystems, on the weather side of the plate. The measured profiles along the plate are compared with the predictions of twonumerical models: an approximate model based on the tertiary interaction theory of Longuet-Higgins & Phillips (J. FluidMech., vol. 12, 1962, p. 333) for plane waves, which provides a steady-state solution, and a fully nonlinear numericalwavetank based on extended Boussinesq equations. In most of the experimental tests, despite the large distance from thewavemaker to the plate and the small amplitude of the incident wave, no steady state is attained by the end of theexploitable part of the records. General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, cole CentraleMarseille, Institut de Recherche sur les Phenomenes Hors Equilibre (IRPHE), cole Centrale Marseille, Institut deRecherche sur les Phnomnes Hors Equilibre (IRPHE), cole Centrale Marseille, Institut de Recherche sur lesPhnomnes Hors Equilibre (IRPHE), 13451 Marseille cedex 20, FranceAuthors:Molin, B. (Ekstern), Kimmoun, O. (Ekstern), Liu, Y. (Ekstern), Remy, F. (Ekstern), Bingham, H. B. (Intern)Pages:363-386Publication date:2010Main Research Area:Technical/natural sciences Publication informationJournal:Journal of Fluid MechanicsVolume:654ISSN (Print):0022-1120Ratings:FI (2012): 2 ISI indexed (2012): yes FI (2011): 2 ISI indexed (2011): yes FI (2010): 2 FI (2009): 2 FI (2008): 1 Original language:EnglishDOIs:10.1017/S0022112010000637 Source:orbitSource-ID:269187Publication: Research - peer-review Journal article Annual report year: 2010

High-order finite difference solution for 3D nonlinear wave-structure interactionThis contribution presents our recent progress on developing an efficient fully-nonlinear potential flow model for simulating3D wave-wave and wave-structure interaction over arbitrary depths (i.e. in coastal and offshore environment). The modelis based on a high-order finite difference scheme OceanWave3D presented in [1, 2]. A nonlinear decomposition of thesolution into incident and scattered fields is used to increase the efficiency of the wave-structure interaction problemresolution. Application of the method to the diffraction of nonlinear waves around a fixed, bottom mounted circular cylinderare presented and compared to the fully nonlinear potential code XWAVE as well as to experiments. General informationState:Published

Organisations:Department of Mechanical Engineering, Coastal, Maritime and Structural Engineering, Scientific Computing, Department of Informatics and Mathematical Modeling, Ecole Centrale de Nantes, Laboratoire de Mcanique des FluidesAuthors:Ducrozet, G. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Ferrant, P. (Ekstern)Keywords: (High-Order Finite Differences, Scattering, OceanWave3D, XWAVE, Nonlinear Decomposition)Pages:225-230Publication date:2010Main Research Area:Technical/natural sciences Publication informationJournal:Journal of HydrodynamicsVolume:22Journal number:5ISSN (Print):1001-6058Ratings:ISI indexed (2012): yes ISI indexed (2011): no Original language:EnglishDOIs:10.1016/S1001-6058(09)60198-0 Source:orbitSource-ID:269177Publication: Research - peer-review Journal article Annual report year: 2010

Hybrid finite difference/BEM solutions of the elliptic mild slope equations General informationState:PublishedOrganisations:Department of Mechanical Engineering, Coastal, Maritime and Structural Engineering, Tehran University,Department of Civil EngineeringAuthors:Zadeh, R. N. (Ekstern), Bingham, H. B. (Intern)Pages:51Publication date:2010 Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:25th International Workshop on Water Waves and Floating Bodies, Harbin, China, 09/05/10 - 09/05/10Documents:iwwwfb25_51.pdf Links:Link to conference website (Open Access) Source:orbitSource-ID:272227Publication: Research - peer-review Article in proceedings Annual report year: 2010

Meshfree simulation of free surface flow and fluid-structure interaction General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Scientific Computing, Department of Informatics and Mathematical ModelingAuthors:Lindberg, O. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern)Publication date:2010 Host publication informationTitle:Proceedings 25th International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:25th International Workshop on Water Waves and Floating Bodies, Harbin, China, 09/05/10 - 09/05/10Source:orbitSource-ID:269063

Publication: Research - peer-review Article in proceedings Annual report year: 2010

Multi-block, boundary-fitted solutions for 3D nonlinear wave-structure interaction General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Scientific Computing, Department of Informatics and Mathematical ModelingAuthors:Bingham, H. B. (Intern), Ducrozet, G. (Intern), Engsig-Karup, A. P. (Intern)Pages:04Publication date:2010 Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesConference:25th International Workshop on Water Waves and Floating Bodies, Harbin, China, 09/05/10 - 09/05/10Documents:iwwwfb25_04.pdf Links:Link to conference website (Open Access) Source:orbitSource-ID:269120Publication: Research - peer-review Article in proceedings Annual report year: 2010

Numerical Analysis on Added Resistance of Ships in Time-domain General informationState:PublishedOrganisations:Department of Mechanical Engineering, Coastal, Maritime and Structural Engineering, Seoul NationalUniversity, Force Technology, DenmarkAuthors:Kim, K. (Ekstern), Joncquez, S. (Ekstern), Kim, Y. (Ekstern), Bingham, H. B. (Intern)Pages:21Publication date:2010 Host publication informationTitle:IWWWFB25Main Research Area:Technical/natural sciencesConference:25th International Workshop on Water Waves and Floating Bodies, Harbin, China, 09/05/10 - 09/05/10Documents:iwwwfb25_21.pdf Links:Link to conference website (Open Access) Source:orbitSource-ID:272231Publication: Research - peer-review Article in proceedings Annual report year: 2010

Second-order Forces and Moments acting on Ships in Waves General informationState:PublishedOrganisations:Department of Mechanical Engineering, Coastal, Maritime and Structural EngineeringAuthors:Joncquez, S. A. G. (Intern), Andersen, P. (Intern), Bingham, H. B. (Intern)Number of pages:184Publication date:Dec 2009 Publication informationPlace of publication:Kgs. Lyngby, DenmarkPublisher:Technical University of Denmark (DTU)

ISBN (Print):978-87-89502-84-7Original language:English Series:DCAMM Special ReportNumber:S108Main Research Area:Technical/natural sciencesDocuments:sagj.pdf Soizic_dansk_resume.pdf Source:orbitSource-ID:258758Publication: Research Ph.D. thesis Annual report year: 2009

A boundary-fitted finite difference solution for nonlinear wave-structure interaction General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Scientific Computing, Department of Informatics and Mathematical ModelingAuthors:Ducrozet, G. (Intern), Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern)Publication date:2009 Host publication informationTitle:Proceedings for 4th Workshop on Water Waves 2009Main Research Area:Technical/natural sciencesConference:Workshop on Water Waves, TU Berlin, Berlin, Germany., 01/01/09Source:orbitSource-ID:253759Publication: Research - peer-review Conference abstract in proceedings Annual report year: 2009

A Comparison of methods for computing the added resistance of ships using a high-order BEM General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Joncquez, S. A. G. (Intern), Bingham, H. B. (Intern), Andersen, P. (Intern)Publication date:2009Event:Abstract from 24th International Workshop on Water Waves and Floating Bodies, Zelenogorsk, RussianFederation.Main Research Area:Technical/natural sciencesDocuments:iwwwfb24_32.pdf Links:Link to conference website (Open Access) Source:orbitSource-ID:243520Publication: Research - peer-review Conference abstract for conference Annual report year: 2009

An efficient flexible-order model for 3D nonlinear water wavesThe flexible-order, finite difference based fully nonlinear potential flow model described in [H.B. Bingham, H. Zhang, Onthe accuracy of finite difference solutions for nonlinear water waves, J. Eng. Math. 58 (2007) 211-228] is extended to threedimensions (3D). In order to obtain an optimal scaling of the solution effort multigrid is employed to precondition a GMRESiterative solution of the discretized Laplace problem. A robust multigrid method based on Gauss-Seidel smoothing is foundto require special treatment of the boundary conditions along solid boundaries, and in particular on the sea bottom. A newdiscretization scheme using one layer of grid points outside the fluid domain is presented and shown to provideconvergent solutions over the full physical and discrete parameter space of interest. Linear analysis of the fundamentalproperties of the scheme with respect to accuracy, robustness and energy conservation are presented together withdemonstrations of grid independent iteration count and optimal scaling of the solution effort. Calculations are made for 3Dnonlinear wave problems for steep nonlinear waves and a shoaling problem which show good agreement with

experimental measurements and other calculations from the literature. General informationState:PublishedOrganisations:Scientific Computing, Department of Informatics and Mathematical Modeling, Coastal, Maritime andStructural Engineering, Department of Mechanical EngineeringAuthors:Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern), Lindberg, O. (Intern)Keywords: (Nonlinear waves, Time domain, Finite differences, Potential flow, Ocean engineering, Multigrid)Pages:2100-2118Publication date:2009Main Research Area:Technical/natural sciences Publication informationJournal:Journal of Computational PhysicsVolume:228Journal number:6ISSN (Print):0021-9991Ratings:FI (2012): 1 ISI indexed (2012): yes FI (2011): 1 ISI indexed (2011): yes FI (2010): 1 FI (2009): 1 FI (2008): 1 Original language:EnglishDOIs:10.1016/j.jcp.2008.11.028 Source:orbitSource-ID:243259Publication: Research - peer-review Journal article Annual report year: 2009

Boundary-fitted solutions for 3D nonlinear water wave-structure interaction General informationState:PublishedOrganisations:Department of Informatics and Mathematical Modeling, Scientific Computing, Department of MechanicalEngineering, Coastal, Maritime and Structural EngineeringAuthors:Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern)Pages:20Publication date:2009 Host publication informationTitle:IWWWFB24Main Research Area:Technical/natural sciencesWorkshop:24th International Workshop on Water Waves and Floating Bodies, Zelenogorsk, Russian Federation, 19/04/09- 19/04/09Documents:iwwwfb24_20.pdf Links:Link to conference website (Open Access) Source:orbitSource-ID:272233Publication: Research - peer-review Article in proceedings Annual report year: 2009

Toward a scalable flexible-order model for 3D nonlinear water wavesFor marine and coastal applications, current work are directed toward the development of a scalable numerical 3D modelfor fully nonlinear potential water waves over arbitrary depths. The model is high-order accurate, robust and efficient forlarge-scale problems, and support will be included for flexibility in the description of structures by the use of curvilinearboundary-fitted meshes. The mathematical equations for potential waves in the physical domain is transformed through

$\sigma$-mapping(s) to a time-invariant boundary-fitted domain which then becomes a basis for an efficient solutionstrategy on a time-invariant mesh. The 3D numerical model is based on a finite difference method as in the original works\cite{LiFleming1997,BinghamZhang2007}. Full details and other aspects of an improved 3D solution can be found in\cite{EBL08}. The new and improved approach for three-dimensional problems employs a GMRES solver with multigridpreconditioning to achieve optimal scaling of the overall solution effort, i.e., directly with $n$ the total number of gridpoints. Grid independent iteration count and optimal scaling has been demonstrated to be independent of the mesh andthe physics. A robust method is achieved through a special treatment of the boundary conditions along solid boundariesusing a fictitious a ghost point technique, and is necessary for a robust multigrid preconditioning strategy. The solutionstrategy is found to be both robust for general nonlinear wave problems, with no need for additional smoothing or filteringover that imposed naturally by the finite difference scheme. By the adjusting the numerical discretization parameters, theaccuracy in dispersion and flow kinematics (accuracy) together with the solution effort (efficiency) can be optimized for themodel to be nearly competitive with dedicated models based on simplified equations, e.g. Boussinesq-type equations. Atthe symposium, we will present examples demonstrating the fundamental properties of the numerical model(OceanWave3D) together with the latests achievements. General informationState:PublishedOrganisations:Scientific Computing, Department of Informatics and Mathematical Modeling, Coastal, Maritime andStructural Engineering, Department of Mechanical EngineeringAuthors:Engsig-Karup, A. P. (Intern), Ducrozet, G. (Intern), Bingham, H. B. (Intern), Dammann, B. (Intern)Keywords: (oceanwave3D)Publication date:2009Event:Abstract from International Conference On Spectral and High Order Methods 2009, Trondheim, Norway.Main Research Area:Technical/natural sciencesSource:orbitSource-ID:247836Publication: Research - peer-review Conference abstract for conference Annual report year: 2009

Velocity potential formulations of highly accurate Boussinesq-type modelsThe highly accurate Boussinesq-type equations of Madsen et al. (Madsen, P.A., Bingham, H.B., Schaffer, H.A., 2003.Boussinesq-type formulations for fully nonlinear and extremely dispersive water waves: Derivation and analysis. Proc. R.Soc. Lond. A 459, 1075-1104; Madsen, P.A., Fuhrman, D.R., Wang, B., 2006. A Boussinesq-type method for fullynonlinear waves interacting with a rapidly varying bathymetry. Coast. Eng. 53, 487-504); Jamois et al. (Jamois, E.,Fuhrman, D.R., Bingham, H.B., Molin, B., 2006. Wave-structure interactions and nonlinear wave processes on theweather side of reflective structures. Coast. Eng. 53, 929-945) are re-derived in a more general framework whichestablishes the correct relationship between the model in a velocity formulation and a velocity potential formulation.Although most work with this model has used the velocity formulation, the potential formulation is of interest because itreduces the computational effort by approximately a factor of two and facilitates a coupling to other potential flow solvers.A new shoaling enhancement operator is introduced to derive new models (in both formulations) with a velocity profilewhich is always consistent with the kinematic bottom boundary condition. The true behaviour of the velocity potentialformulation with respect to linear shoaling is given for the first time, correcting errors made by Jamois et al. (Jamois, E.,Fuhrman, D.R., Bingham, H.B., Molin, B., 2006. Wave-structure interactions and nonlinear wave processes on theweather side of reflective structures. Coast. Eng. 53, 929-945). An exact infinite series solution for the potential is obtainedvia a Taylor expansion about an arbitrary vertical position z=(z) over cap. For practical implementation however, thesolution is expanded based on a slow variation of (z) over cap and terms are retained to first-order. With shoalingenhancement, the new models obtain a comparable accuracy in linear shoaling to the original velocity formulation.General consistency relations are also derived which are convenient for verifying that the differential operators satisfy apotential flow and/or conserve mass up to the order of truncation of the model. The performance of the new formulation isvalidated using computations of linear and nonlinear shoaling problems. The behaviour on a rapidly varying bathymetry isalso checked using linear wave reflection from a shelf and Bragg scattering from an undulating bottom. Although the newmodels perform equally well for Bragg scattering they fail earlier than the existing model for reflection/transmissionproblems in very deep water. General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Bingham, H. B. (Intern), Madsen, P. A. (Intern), Fuhrman, D. R. (Intern)Keywords: (Nonlinear waves, Bragg scattering, Potential flow, Wave reflection/transmission, Finite difference method,Boussinesq-type equations)Pages:467-478Publication date:2009Main Research Area:Technical/natural sciences Publication information

Journal:Coastal EngineeringVolume:56Journal number:4ISSN (Print):0378-3839Ratings:FI (2012): 2 ISI indexed (2012): yes FI (2011): 2 ISI indexed (2011): yes FI (2010): 2 FI (2009): 2 FI (2008): 2 Original language:EnglishDOIs:10.1016/j.coastaleng.2008.10.012 Source:orbitSource-ID:243232Publication: Research - peer-review Journal article Annual report year: 2009

DG-FEM solution for nonlinear wave-structure interaction using Boussinesq-type equationsWe present a high-order nodal Discontinuous Galerkin Finite Element Method (DG-FEM) solution based on a set of highlyaccurate Boussinesq-type equations for solving general water-wave problems in complex geometries. A nodal DG-FEM isused for the spatial discretization to solve the Boussinesq equations in complex and curvilinear geometries which amendsthe application range of previous numerical models that have been based on structured Cartesian grids. The Boussinesqmethod provides the basis for the accurate description of fully nonlinear and dispersive water waves in both shallow anddeep waters within the breaking limit. To demonstrate the current applicability of the model both linear and mildly nonlineartest cases are considered in two horizontal dimensions where the water waves interact with bottom-mounted fullyreflecting structures. It is established that, by simple symmetry considerations combined with a mirror principle, it ispossible to impose weak slip boundary conditions for both structured and general curvilinear wall boundaries whilemaintaining the accuracy of the scheme. As is standard for current high-order Boussinesq-type models, arbitrary wavescan be generated and absorbed in the interior of the computational domain using a flexible relaxation technique applied onthe free surface variables. General informationState:PublishedOrganisations:Scientific Computing, Department of Informatics and Mathematical Modeling, Coastal, Maritime andStructural Engineering, Department of Mechanical EngineeringAuthors:Engsig-Karup, A. P. (Intern), Hesthaven, J. (Intern), Bingham, H. B. (Intern), Warburton, T. (Ekstern)Keywords: (Grid adaption, nonlinear and dispersive water waves, discontinuous Galerkin finite element method, high-order Boussinesq-type equations, unstructured and curvilinear grids, Wave-structure interaction)Pages:197-208Publication date:Mar 2008Main Research Area:Technical/natural sciences Publication informationJournal:Coastal EngineeringVolume:55Journal number:3ISSN (Print):0378-3839Ratings:FI (2012): 2 ISI indexed (2012): yes FI (2011): 2 ISI indexed (2011): yes FI (2010): 2 FI (2009): 2 FI (2008): 2 Original language:EnglishDOIs:10.1016/j.coastaleng.2007.09.005

Source:orbitSource-ID:221720Publication: Research - peer-review Journal article Annual report year: 2008

An efficient flexible-order model for coastal and ocean water wavesCurrent work are directed toward the development of an improved numerical 3D model for fully nonlinear potential waterwaves over arbitrary depths. The model is high-order accurate, robust and efficient for large-scale problems, and supportwill be included for flexibility in the description of structures. The mathemathical equations for potential waves in thephysical domain is transformed through $\sigma$-mapping(s) to a time-invariant boundary-fitted domain which thenbecomes a basis for an efficient solution strategy. The improved 3D numerical model is based on a finite differencemethod as in the original works \cite{LiFleming1997,BinghamZhang2007}. The new and improved approach employs aGMRES solver with multigrid preconditioning to achieve optimal scaling of the overall solution effort, i.e., directly with $n$the total number of grid points. A robust method is achieved through a special treatment of the boundary conditions alongsolid boundaries, and is necessary for a robust multigrid preconditioning strategy. Full details and other aspects of the 3Dsolution will appear in \cite{EngsigKarupBinghamLindberg2008}. At the symposium, we will present examplesdemonstrating the fundamental properties of the numerical model together with the latests achievements. General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Engsig-Karup, A. P. (Intern), Bingham, H. B. (Intern), Lindberg, O. (Intern)Publication date:2008Event:Abstract from First American Academy of Mechanics Conference, New Orleans, .Main Research Area:Technical/natural sciencesDocuments:paper.pdf Source:orbitSource-ID:223364Publication: Research - peer-review Conference abstract for conference Annual report year: 2008

Efficient Solution of the 3D Laplace Problem for Nonlinear Wave-Structure Interaction General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Scientific Computing, Department of Informatics and Mathematical ModelingAuthors:Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern)Publication date:2008 Host publication informationTitle:ASME 27. International Conference on Offshore Mechanics and Arctic EngineeringPublisher:American Society of Mechanical EngineersISBN (Print):0791838218Main Research Area:Technical/natural sciencesConference:27th International Conference on Offshore Mechanics and Arctic Engineering, Estoril, Portugal, 15/06/08 -15/06/08Documents:BinghamEngsigKarupOMAE2008_final.pdf Source:orbitSource-ID:233417Publication: Research - peer-review Article in proceedings Annual report year: 2008

Improved velocity potential formulations of highly accurate Boussinesq-type models General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Scientific Computing, Department of Informatics and Mathematical ModelingAuthors:Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Fuhrman, D. R. (Intern), Madsen, P. A. (Intern)

Pages:191-203Publication date:2008 Host publication informationTitle:31. International Conference on Coastal EngineeringVolume:1-5Publisher:American Society of Civil EngineersMain Research Area:Technical/natural sciencesConference:31st International Conference on Coastal Engineering, Hamburg, Germany, 31/08/08 - 31/08/08Documents:BinghamEtAlICCE2008Paper.pdf Source:orbitSource-ID:233427Publication: Research - peer-review Article in proceedings Annual report year: 2008

Multigrid preconditioning for efficient solution of the 3D Laplace problem for wave-body interaction General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Bingham, H. B. (Intern), Engsig-Karup, A. P. (Intern), Lindberg, O. (Intern)Publication date:2008 Host publication informationTitle:International Workshop on Water Waves and Floating BodiesMain Research Area:Technical/natural sciencesWorkshop:23rd International Workshop on Water Waves and Floating Bodies, Jeju Island, Korea, Republic of, 13/04/08 -13/04/08Documents:BinghamEtAlIWWWFB23_submit.pdf Source:orbitSource-ID:223365Publication: Research - peer-review Article in proceedings Annual report year: 2008

Numerical analysis of ship-ship interaction by a high-order potential flow code with ship motions General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical EngineeringAuthors:Shin, K. W. (Intern), Bingham, H. B. (Intern), Andersen, P. (Intern)Keywords: (ship-ship interaction, ship manoeuvring)Publication date:2008 Host publication informationTitle:11. Numerical Towing Tank SymposiumPlace of publication:BrestPublisher:ENSIETA / TUHHMain Research Area:Technical/natural sciencesConference:11th Numerical Towing Tank Symposium, Brest, France, 07/09/08 - 07/09/08Source:orbitSource-ID:232334Publication: Research - peer-review Article in proceedings Annual report year: 2008

Validation of Added Resistance Computations by a Potential-Flow Boundary-Element Method General informationState:PublishedOrganisations:Coastal, Maritime and Structural Engineering, Department of Mechanical Engineering, Flight SafetyTechnology

Authors:Joncquez, S. A. G. (Intern), Bingham, H. B. (Intern), Andersen, P. (Intern), Kring, D. (Ekstern)Publication date:2008 Host publication informationTitle:Proceedings of the 27th Symposium on Naval HydrodynamicsPublisher:Office of Naval Research, U.S.A.Main Research Area:Technical/natural sciencesConference:Symposium on Naval Hydrodynamics, Seoul, S. Korea, 01/01/08Documents:joncquezfinal.pdf Source:orbitSource-ID:233436Publication: Research - peer-review Article in proceedings Annual report year: 2008

Unstructured nodal DG-FEM solution of high-order Boussinesq-type equationsThe main objective of the present study has been to develop a numerical model and investigate solution techniques forsolving the recently derived high-order Boussinesq equations of \cite{MBL02} in irregular domains in one and twohorizontal dimensions. The Boussinesq-type methods are the simplest alternative to solving full three-dimensional waveproblems by e.g. Navier-Stokes equations, which can capture all the important wave phenomena such as diffraction,refraction, nonlinear wave-wave interactions and interaction with structures. The main goal can be reached by using multi-domain methods with support for a spatial discretization based onunstructured grids. In the current work, a standard method of lines approach has been adapted, and the method of choicefor the spatial discretization is the nodal Discontinuous Galerkin Finite element method (DG-FEM), which provides a highlyflexible basis for the model. This method is combined with an explicit Runge-Kutta method for the temporal discretization.The resulting discrete set of equations enables us to simulate water waves accurately in complex geometric settings andpossibly employ local adaption techniques to optimize the computational effort. %As of today, the high-order Boussinesq equations represent the most advanced set of Boussinesq-type equationscapable of modelling nonlinear and dispersive waves from shallow to deep water without the practical limitations ofclassical Boussinesq-type equations. The high-order Boussinesq equations constitute a highly complex system of coupled equations which put any numericalmethod to the test. The main problems that need to be overcome to solve the equations are the treatment of stronglynonlinear convection-type terms and spatially varying coefficient terms; efficient and robust solution of the resultant time-dependent linear system; and the numerical treatment of high-order and cross-differential derivatives. The suggestedsolution strategy of the current work is based on a collocation approach where the DG-FEM is used to approximate spatialderivatives and the boundary conditions are imposed weakly using a symmetry technique. Since collocation methods areprone to aliasing errors, various anti-aliasing strategies are applied for the stabilization of the models. A practical andrelatively straightforward discretization is applied, which is based on a simple treatment of slip boundary conditions at wallsurfaces. A linear Fourier analysis has been applied to obtain generic analytical results which can be used for validating the discreteimplementation and provide the basis for choosing stable discretization parameters as well as giving new insight into theproperties of the high-order Boussinesq equations. Remarkably, it is demonstrated that the linear eigenspectra of thelinearized semi-discrete equation system is bounded and hence the stable time increment is not dictated by the spatialdiscretization. This is a favorable property for explicit time-integration schemes as the stable time increment is not subjectto severe restrictions which can affect the performance of the scheme. It is demonstrated that the discrete properties ofboth DG-FEM and finite difference methods can be discretized to mimic the analytical properties. It is investigated mathematically and demonstrated numerically how the relaxation method of \cite{LD83} can be applied inspectral/$hp$ multi-domain methods for both accurate internal wave generation of arbitrary wave fields and efficientabsorption near domain boundaries. The method is considered to be particular attractive for wave generation purposes foruse with high-order Boussinesq models as it alleviates the need for specifying consistent boundary conditions, andimportantly, it is a very straightforward and flexible method. The DG-FEM models have been applied to a number of tests in both one and two horizontal dimensions with the objectiveof both validating the setup against known analytical and experimental test results, and at the same time demonstratingthe attractive properties of the method. It has been demonstrated that difficult nonlinear and dispersive wave problems canbe solved accurately in one horizontal dimension. In two horizontal dimensions it has been demonstrated that the modelcan solve problems in both regular and irregular geometries and by comparison with analytical results it is shown that theresults are in general in excellent agreement. Thus, it has been established that the DG-FEM can be used to solve this relatively complicated system of equations. Thecomputational efficiency of the method has yet to be demonstrated.

General informationState:PublishedOrganisations:Scientific Computing, Department of Informatics and Mathematical Modeling, Coastal, Maritime andStructural En