Download - LectureSlides10_openfoam
Introduction to OpenFOAM
Ole Lindberg
Section of Coastal, Maritime and Structural Engineering
Department of Mechanical EngineeringTechnical University of Denmark
November 18, 2009
Ole Lindberg Introduction to OpenFOAM
About OpenFOAM
OpenFOAM: Open Field Operation and Manipulation.
A open source CFD toolbox written in C++ for the Linux operationsystem.
It is produced by OpenCFD Ltd, freely available and open source.
Licensed under the GNU General Public Licence.
Homepage: http://www.opencfd.co.uk/
Ole Lindberg Introduction to OpenFOAM
Why OpenFOAM?
OpenFOAM is open source.
It is the best open source CFD program available.
The quality of the C++ code is very high.
OpenFOAM has almost all standard finite volume methodsimplemented.
It comes with a fairly good documentation.
OpenFOAM has an easy to use high level object-orientatedprogramming interface.
High licence fees on other commercial CFD packages like CFX orFluent.
The industry is very interested in OpenFOAM.
Ole Lindberg Introduction to OpenFOAM
Numerical methods in OpenFOAM
OpenFOAM is a Finite Volume CFD program using both structured andunstructured meshes.
Some of the numerical methods in OpenFOAM are:
Time integration:
Backward Euler: Euler
Steady state solver: steadyState
Crank-Nicholson: CrankNicholson
Gradient, divergence, Laplacian and interpolation schemes:
Second order central difference: linear
Fourth order central difference: cubic
First order upwind: upwind
First/second order upwind: linearUpwind
Ole Lindberg Introduction to OpenFOAM
Numerical methods in OpenFOAM
Linear solvers:
Preconditioned (bi-)conjugate gradient: PCG, PBiCG
Basic iterative method (e.g. Gauss-Seidel): smoothSolver
Geometric and algebraic multigrid: GAMG
Turbulence models:
k-ε: kEpsilon
k-ω: kOmegaSST
LES
Ole Lindberg Introduction to OpenFOAM
Boundary conditions in OpenFOAM
The boundary conditions are setup for each of the flow variables (U, p,etc).
Some of the boundary types are:
Base types: patch, wall, symmetry, empty, cyclic
Primitive types: fixedValue, fixedGradient, mixed, calculated
Derived types: inletOulet, outletInlet, movingWallVelocity, slip
Ole Lindberg Introduction to OpenFOAM
Precompiled solvers
OpenFOAM comes with many of precompiled solvers ready for use.
The most important of these are:
laplacianFoam Solves a simple Laplace equation, e.g. for thermal diffusion.
potentialFoam Potential flow solver.
scalarTransportFoam Solves a transport equation for a passive scalar.
icoFoam Transient solver for incompressible and laminar flow.
simpleFoam Steady-state solver for incompressible and turbulent flow.
pisoFoam Transient solver for incompressible and turbulent flow.
sonicFoam Transient solver for sonic flow of a compressible gas.
interFoam Two phase incompressible flow, using the VOF method.
dnsFoam Direct numerical simulation of isotropic turbulence.
electrostaticFoam Solver for electrostatics.
Ole Lindberg Introduction to OpenFOAM
Mesh generation in OpenFOAM
OpenFOAM comes with a mesh generation tool:blockMesh
Block structured meshes.
Curved internal and external boundaries.
The mesh is setup in a script (no GUI).
Good for small grids.
External mesh generation is also possible with the tools:ansysToFoam, cfxToFoam, gmshToFoam and more ...
Block structured mesh.
Unstructured mesh.
Block structured mesh and unstructured mesh in combination.
Large and complex grids can be made with a GUI in e.g. ANSYSICEM (proprietary) or Gmsh (open source).
Ole Lindberg Introduction to OpenFOAM
Installation of OpenFOAM
The latest official version of OpenFOAM is available on:http://www.opencfd.co.uk/openfoam/download.html
Both 32bit or 64bit versions are available.Download the packages:
OpenFOAM-1.6.General.gtgz
OpenFOAM-1.6.linuxGccDPOpt.gtgz
ThirdParty.General.gtgz
ThirdParty.linuxGcc.gtgz
and save the files in the directory structure as described on the downloadpage.Unpack the files, e.g.:tar xzf OpenFOAM-1.6.General.gtgz
Read the file$HOME/OpenFOAM/OpenFOAM-1.6/README
and follow the instructions.
Ole Lindberg Introduction to OpenFOAM
Installation of ParaView
OpenFOAM uses ParaView as flow visualisation tool, seehttp://www.paraview.org/.
ParaView uses Qt (a C++ GUI library).
Install Qt from the repository of your Linux distribution.
Ole Lindberg Introduction to OpenFOAM
Setup a new OpenFOAM simulation
Start a new OpenFOAM case:mkdir $HOME/OpenFOAM/$USER-1.6/run/MySimulation
Go to your new case directory:cd $HOME/OpenFOAM/$USER-1.6/run/MySimulation
Copy one of the tutorials into your case:cp -r $HOME/OpenFOAM/$USER-1.6/run/incompressible/icoFoam/cavity/* .
Set physical parameters in:./constant/transportProperties
Setup the mesh in:./constant/polyMesh/blockMeshDict
Setup the initial and boundary conditions in:./0/U (and p, k, epsilon etc.)
Set the start time, end time and Courant number in:./system/controlDict
Setup temporal schemes and spatial finite volume schemes in:./system/fvSchemes
Setup linear solvers in:./system/fvSolution
Ole Lindberg Introduction to OpenFOAM
Basic working cycle
Go to your case directory:cd $HOME/OpenFOAM/$USER-1.6/run/MySimulation
Run the mesh generation:blockMesh
Run the simulation:icoFoam
Do some post-processing, e.g. calculation of vorticity:vorticity
View the solution using paraView:paraFoam
In trouble?Read the manual:$HOME/OpenFOAM/OpenFOAM-1.6/doc/Guides-a4/UserGuide.pdf
look at the tutorials:$HOME/OpenFOAM/OpenFOAM-1.6/tutorials
or search the OpenFOAM forum:http://www.cfd-online.com/Forums/openfoam/
Ole Lindberg Introduction to OpenFOAM
Mesh generation with Gmsh
Install Gmsh from the repository of your Linux distribution or download ithere http://www.geuz.org/gmsh/
For introductions to Gmsh see:http://www.geuz.org/gmsh/doc/texinfo/
http://www.geuz.org/gmsh/screencasts/
http://ffep.sourceforge.net/Download/gui_tutorial.pdf
Go to your OpenFOAM case folder:cd $HOME/OpenFOAM/$USER-1.6/run/MySimulation
Download the Gmsh file mesh.geo from file sharing on Campusnet andplace it in the folder:$HOME/OpenFOAM/$USER-1.6/MySimulation/constant/gmshMesh/
Run Gmsh:gmsh -3 constant/gmshMesh/mesh.geo -o constant/gmshMesh/mesh.msh
Convert the gmsh mesh to OpenFOAM format:gmshToFoam constant/gmshMesh/mesh.msh
Setup the your OpenFOAM flow case, e.g. boundary conditions, andstart calculating.
Ole Lindberg Introduction to OpenFOAM
