advancing interfacial flow simulations in openfoams3-eu-west-1.amazonaws.com ›...
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Advancing interfacial flow
simulations in OpenFOAM
Johan Rønby
DANSIS seminar
Computational Techniques for Gas-Liquid Flows,
May 16, 2018
Artificial surf reef in Australia Offshore wind turbines in Denmark
OpenFOAM for interfacial flow simulations at DHI
#3
The Volume-of-Fluid (VOF) method
Cell volume fractions: 0 ≤ 𝛼𝑖 ≤ 1Video link
Interface advection in OpenFOAM/interFoam
Algebraic VOF method:
Interface compression
with MULES limiter
Not shape preserving!
Do alternatives exist?
Geometric VOF methods
Complex and expensive
#4
Simple pure advection test:
Circle in constant flow
Video link
#5
isoAdvector: a new geometric VOF method
Novelty:
1.
Interface reconstruction
based on isosurfaces
2.
Interface advection/
VOF fluxing step
based on geometric
plane-polygon
intersection.
More conceptual details in Roenby, Bredmose and Jasak, Royal Society Open Science 3: 160405
Video link
#6
Circular disc in constant flow on hex mesh
dx = Radius/5
CFL = 0.5
Exact solution
0.5 contour
0.01 contour
0.99 contour
isoAdvector MULES
IsoAdvector MULES HRIC CICSAM (0.5)
#7
dx = R/5
dx = R/10
dx = R/2.5
CFL = 0.5
IsoAdvector is slightly
faster than HRIC and
CICSAM, and 2-4 times
faster than MULES
Circular disc in constant flow on hex mesh
#8
IsoAdvector works on unstructured meshes
Pure advection test cases with tetrahedral cells:
Sphere in constant velocity field Sphere in analytical, time-
reversed velocity field
Video link Video link
#9
For coupling to p-U solver see J Roenby, H Bredmose, H Jasak, "IsoAdvector: Geometric VOF on general meshes", 11th OpenFOAM Workshop book (in print)
Coupling isoAdvector with p-U solver
DamBreak case
Video link
Wave propagation
#10
Stream function wave in periodic domain
Depth = 20 m, Wave height = 10 m, wave period = 10 s
From conference paper: Roenby, Larsen, Bredmose & Jasak, "A new volume-of-fluid method in OpenFOAM", MARINE 2017
Surface after 10 periodsExact solution
Square cells
Tall cells
Flat cells
Fire sprinklers
#14
Article link
Automatic mesh refinement (AMR)
#15
Testing with Erkki Laurila and Ville Vuorinen from Alto University
MULES isoAdvector
Video link
#16 Submitted to International Journal of Multiphase Flow
Original
isoAdvector
reconstruction
New reconstruction method
isoAdvector reconstruction
Submitted to Journal of Computational Physics
Preprint: arxiv.org/abs/1801.05382
• isoAdvector: a new VOF method for general unstructured meshes
• Accuracy: comparable to existing geometric VOF schemes
• Efficiency: similar to fastest algebraic VOF schemes
• Availability: Integrated in OpenFOAM.com version and available
for OpenFOAM.org version on www.github.com/isoAdvector
• Future development: Moving meshes, Automatic mesh refinement,
surface tension, compressible flows, larger time steps, ...
• More info: www.stromning.com/isoAdvector
Summary
