Talk at IJL's seminar on 21/01/2018

1. 2M
OpenFOAM®: open source
finite volume modelling
framework
Alexey Matveichev, O2M Solutions

2. 2M
This offering is not approved or endorsed
by OpenCFD Limited, producer and
distributor of the OpenFOAM software via
www.openfoam.com, and owner of the
OPENFOAM® and OpenCFD® trade
marks.

3. • What is OpenFOAM® and what can it do for me
• Examples
• Droplet formation and detachment
• Electron beam melting
• Vacuum arc remelting
• Solidification of steel ingots
• OpenFOAM®: idiosyncrasies and annoyances
Outline
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4. Short OpenFOAM® history (official one)
• 199x – Weller started development of what will become OpenFOAM®
• 2004 – OpenCFD® is created (Weller, Greenshields, Janssens)
• Aug. 2011 – OpenCFD® is bought by SGI
• Sep. 2012 – OpenCFD® is bought by ESI
• 2014 – Weller & Greeshields left ESI to start CFD Direct
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5. OpenFOAM® history (Jasak’s apocryphe)
• 199x – development started by Charlie Hill
• 1993 – Jasak and Weller became primary developers
• 2000 – Jasak and Weller created Nabla Ltd, main developer of FOAM
• 2004 – due to internal conflict Nabla Ltd ceased to exist, OpenFOAM®
released under GPL license
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6. OpenFOAM®: shipped capabilities
• Mesh generation/manipulation
• Using dictionary for blocks description
• Generation from STLs
• Import
• Solvers
• Incompressible and compressible Navier-Stokes on arbitrary (moving) meshes
• Combustion
• Heat transfer
• Multi-phase flows (VoF)
• Solid body deformation
• Pre-processing
• Turbulence generation
• Field initialisation
• Post-processing
• Probing and sampling
• Calculations on flow field
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7. OpenFOAM®: advantages
• It available, it is free, one can freely modify it
• C++: operator overloading and templates
• Run-time selectable behaviour
• Extensibility
• Lots of readily available physicochemical models
• Steep learning curve
• Community
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8. OpenFOAM® advantages: operator overloading and templates
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{
…
// Updating sources with new temperature
greybody_radiation.Correct();
cooling_circuit.Correct();
fvScalarMatrix temperature_equation(
fvm::ddt(T)
+ fvm::div(phi, T)
- fvm::laplacian(alphaEff, T)
+ solidification.latent_heat());
…
// Adding energy brought by the load
load.AddTemperatureSource(temperature_equation);
temperature_equation.relax();
temperature_equation.solve();
rhok = 1.0 - alloy.betaT()*(T - alloy.Tref());
}

9. OpenFOAM® advantages: operator overloading and templates
9
namespace Foam
{
template<class T>
inline void Swap(T& a, T& b)
{
T tmp = a;
a = b;
b = tmp;
}
} // End namespace Foam
• Express type-independent algorithms (typical example - sort)
• Allow compile time specialisation of the function and data structures,
aka safe alternative to preprocessor
• Avoid certain verbosity

10. OpenFOAM® advantages: run-time selectable behaviour
10
• Simulation behaviour is described in a set of dictionaries with relatively
documented syntax
• Run-time selection mechanism is well-polished, though could be
verbose
solvers
{
p
{
solver GAMG;
tolerance 1e-08;
relTol 0.1;
smoother DICGaussSeidel;
}
U
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-08;
relTol 0.01;
}
}

11. OpenFOAM® advantages: extensibility and freedom
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• Well defined API and procedure for extension
• User can start from code stream (coded initial/boundary conditions,
coded post-processing)
• And then proceed with implementation of custom library
• If standard solvers/libraries are completely unsuitable for the purpose,
everything could be rewritten from scratch

12. OpenFOAM® examples: drop formation and detachment
Ti drop(s) (𝜚 = 4200 kg/m3, 𝛾 = 1.2 N/m)
Flow rate ~ 0.1 mm/s
8M cells, decomposed into 84 subdomains, 0.5 T of data
* P. Chapelle, C. Noël, A. Risacher, J. Jourdan, A.
Jardy, J. Jourdan, Optical investigation of the
behavior of the electric arc and the metal transfer
during vacuum remelting of a Ti alloy, Journal of
Materials Processing Technology, vol. 214,
2268-2275 (2014).
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13. OpenFOAM® examples: electron beam melting
Problem
Create a 3D solver for modelling of remelting in
electron beam furnace.
Solver should be capable of describing the
following phenomena:
• Electron beam energy deposition.
• Phase change.
• Momentum and heat transfer inside
specimen.
• Turbulence development in the liquid pool.
• Cooling through radiation and water
cooling circuit.
• Evaporation of solutes.
Electron beam
Radiative
heat transfer
Water cooling
13

14. OpenFOAM® examples: electron beam melting
Specimen geometry
Beam pattern
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15. OpenFOAM® examples: electron beam melting
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16. OpenFOAM® examples: vacuum arc remelting
Problem
Create a 3D solver for modelling of vacuum arc
remelting process.
Solver should address the following phenomena:
• Ingot growth.
• Electric arc energy deposition.
• Electric current and induced magnetic field,
volumetric forces created by interaction between
them.
• External magnetic field
• Phase change.
• Momentum, heat, and mass transfer inside
ingot.
• Turbulence development in the liquid pool.
• Cooling through radiation and water cooling
circuit.
• Evaporation of solutes.
• Macrosegregation.
DC
Pump
Water in
Water out
Electrode
Solid ingot
Liquid pool
Copper crucible
Arc
Gas
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17. OpenFOAM® examples: vacuum arc remelting
Mesh
growth
Crucible
cooling
Crucible
cooling
Load matter
Arc
Radiation
17

18. OpenFOAM® examples: vacuum arc remelting
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19. OpenFOAM® examples: vacuum arc remelting
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20. OpenFOAM® examples: vacuum arc remelting
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21. OpenSolid: modelling steel ingot solidification
• Static solid
• Binary eutectic alloy
• Constant phase-dependent
thermophysical properties (heat
diffusivity and conductivity)
• Single domain – ingot
• Laminar flow
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In collaboration with

22. OpenSolid: SMACS benchmark
• H=6 cm, W/2 = 5 cm
• Alloy: Pb-18%wt-Sn
• fully liquid
• at Tliquidus
• hc = 400 W·m-2·K-1
• Text = 25 °C
Solid, 600 s OpenSolid, 600 s22

23. OpenSolid: SMACS benchmark, from 20x24 to 1600x1920
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24. OpenSolid: A&D octogonal ingot
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H: 1,96 m
D: 0.65 m

25. OpenSolid: A&D octogonal ingot, mesh convergence
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7 mm 5 mm 2 mm 1 mm 0.5 mm

26. OpenFOAM®: idiosyncrasies and annoyances
• Fragmentation, versioning, packaging
• C++: heavy use of preprocessor and templates
• Weight
• Documentation or lack of
• License
• Community
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27. OpenFOAM®: fragmentation, versioning, packaging
OpenFOAM
(Weller & Co)
foam-extend
(Jasak & Co)
OpenFOAM+
(ESI)
Caelus-CML
(Applied CCM)
HelyxOS
(ENGYS)
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28. OpenFOAM®: fragmentation, versioning, packaging
OpenFOAM OpenFOAM+ foam-extend
6 v1812 4.0
Ubuntu, Docker, sources
Ubuntu, Docker,
Windows, sources
Ubuntu, Windows,
macOS, Fedora,
sources
28

29. OpenFOAM®: C++: heavy use of preprocessor and templates
error-example.C: Dans la fonction « int main(int, char**) »:
error-example.C:44:37: error: pas de fonction correspondant à l'appel
« gSum(Foam::tmp<Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>
>) »
Info<< gSum(fvc::grad(T)) << endl;
In file included from $FOAM_SRC/OpenFOAM/lnInclude/Field.C:87
from $FOAM_SRC/OpenFOAM/lnInclude/Field.H:40
from $FOAM_SRC/OpenFOAM/lnInclude/scalarFiel
from $FOAM_SRC/OpenFOAM/lnInclude/dimensionS
from $FOAM_SRC/OpenFOAM/lnInclude/dimensione
from $FOAM_SRC/OpenFOAM/lnInclude/dimensione
from $FOAM_SRC/OpenFOAM/lnInclude/TimeState.
from $FOAM_SRC/OpenFOAM/lnInclude/Time.H:47,
from $FOAM_SRC/finiteVolume/lnInclude/fvCFD.
from error-example.C:18:
$FOAM_SRC/OpenFOAM/lnInclude/FieldFunctions.C:543:24: note: c
G_UNARY_FUNCTION(Type, gSum, sum, sum)
^
$FOAM_SRC/OpenFOAM/lnInclude/FieldFunctions.C:533:12: note: d
ReturnType gFunc(const UList<Type>& f, const label comm)
^~~~~
$FOAM_SRC/OpenFOAM/lnInclude/FieldFunctions.C:543:24: note:
G_UNARY_FUNCTION(Type, gSum, sum, sum)
^
[— several pages later —]
$FOAM_SRC/OpenFOAM/lnInclude/FieldFieldFunctions.C:400:12: no
returnType func(const tmp<FieldField<Field, Type>>& tf1)
^~~~
$FOAM_SRC/OpenFOAM/lnInclude/FieldFieldFunctions.C:559:1: not
G_UNARY_FUNCTION(Type, gSum, sum, sum)
^~~~~~~~~~~~~~~~
error-example.C:44:37: note: types « Foam::FieldField<Field, Type> » et « Foam::Geometri
Info<< gSum(fvc::grad(T)) << endl;
^ 29

30. OpenFOAM®: weight
$ pwd
/Users/alexey/OpenFOAM/OpenFOAM-6/src
$ ls
Allwmake* finiteVolume/ rigidBodyDynamics/
ODE/ functionObjects/ rigidBodyMeshMotion/
OSspecific/ fvAgglomerationMethods/ sampling/
OpenFOAM/ fvMotionSolver/ semiPermeableBaffle/
Pstream/ fvOptions/ sixDoFRigidBodyMotion/
TurbulenceModels/ genericPatchFields/sixDoFRigidBodyState/
atmosphericModels/ lagrangian/ surfMesh/
combustionModels/ mesh/ thermophysicalModels/
conversion/ meshTools/ topoChangerFvMesh/
dummyThirdParty/ parallel/ transportModels/
dynamicFvMesh/ randomProcesses/ triSurface/
dynamicMesh/ regionCoupled/ waves/
engine/ regionModels/
fileFormats/ renumber/
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31. OpenFOAM®: documentation
• OpenFOAMUseGuide-(A4|USletter).pdf in distribution
• Doxygen generated API reference
• Due to fast evolution OpenFOAMProgrammerGuide was removed from
distribution (becomes outdated too fast)
• « Source code is documentation » philosophy
• Dictionary syntax is usually documented in headers of models, often
comments are misleading/outdated
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32. • Office 1-008
• OpenFOAM® consulting
• On-demand development
• Transform PDEs into OpenFOAM® C++ code
• Transform process into a set of PDE/ODEs and transform them
OpenFOAM® C++ code
O2M Solutions
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33. 2M
Thank you!