| a_bassolillo |
August 18, 2021 11:33 |
Struggling with convergence inviscid rhoCentralFoam
Dear all,
I am writing to ask for help in a problem I am facing regarding the inviscid transonic simulation of the flow around a RAE2822.
I am here attaching the files that could be useful to understand what I'm talking about. Since the solution of each time step is explicit, convergence cannot be assessed looking at the residuals, since their values is always equal to zero.
Since I am studying the steady 2D behaviour of an airfoil I would like to stop the simulation when the drag coefficient arrives at steady state, but this condition seems to be impossible to reach, I have tried to set a total pressure inlet bc to improve stability, but while the flowfield obtained (after a quite low number of iterations) seems reasonable with the shock in the correct position (given by NASA literature), the aerodynamic coefficient values calculated by rhoCentralFoam show a significant oscillation. This oscillation does not allow me to consider this solution at convergence. Even increasing a lot the number of iterations, this problem remains unsolved.
As mesh I am using a structured C-grid, produced with the curiosityfluids tool. I tried several combination of the values, ranging from 30.000 to 120.000 elements.
I am now attaching the files describing my configuration.
CONTROLDICT
Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
application rhoCentralFoam;
startFrom latestTime;
startTime 0;
stopAt endTime;
endTime 0.1;
deltaT 3e-6;
writeControl adjustableRunTime;
writeInterval 0.005;
purgeWrite 0;
writeFormat ascii;
writePrecision 8;
writeCompression off;
timeFormat general;
timePrecision 6;
runTimeModifiable true;
functions
{
#includeFunc MachNo
#includeFunc residuals
forces
{
type forceCoeffs;
libs ("libforces.so");
writeControl timeStep;
writeControl timeStep;
writeInterval 1;
pName p;
UName U;
log true;
patches
(
airfoil
);
rhoInf 0.5966;
CofR (0 0 0);
liftDir (-0.0403 0.9992 0);
dragDir (0.9992 0.0403 0);
pitchAxis (0 0 1);
magUInf 233.6216;
lRef 1;
Aref 1;
}
}
FVSCHEMES
Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
fluxScheme Kurganov;
ddtSchemes
{
default CrankNicolson 0;
}
gradSchemes
{
default cellLimited Gauss linear 1;
grad(U) cellLimited Gauss linear 1;
}
divSchemes
{
default none;
div(tauMC) Gauss linearUpwind;
div(phi,U) Gauss linearUpwindV grad(U);
div(phi,omega) Gauss linearUpwind default;
div(phi,k) Gauss linearUpwind default;
div((nuEff*dev(T(grad(U))))) Gauss linear;
}
laplacianSchemes
{
default Gauss linear limited 1;
}
interpolationSchemes
{
default linear;
reconstruct(rho) vanLeer;
reconstruct(U) vanLeerV;
reconstruct(T) vanLeer;
}
snGradSchemes
{
default limited 1;
}
// ************************************************************************* //
FVSOLUTION
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
"(rho|rhoU|rhoE)"
{
solver diagonal;
}
U
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-09;
relTol 0.01;
}
h
{
$U;
tolerance 1e-10;
relTol 0;
}
}
// ************************************************************************* //
Folder 0/
U
Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Uinlet (233.4317 9.4164 0);
dimensions [0 1 -1 0 0 0 0];
internalField uniform $Uinlet;
boundaryField
{
farfield
{
type freestreamVelocity;
freestreamValue uniform $Uinlet;
value uniform $Uinlet;
}
airfoil
{
type slip;
}
frontAndBack
{
type empty;
}
#includeEtc "caseDicts/setConstraintTypes"
}
// ************************************************************************* //
0/p
Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
pOut 43765;
dimensions [1 -1 -2 0 0 0 0];
internalField uniform $pOut;
boundaryField
{
farfield
{
type fixedValue;
value uniform 43765;
}
airfoil
{
type zeroGradient;
}
frontAndBack
{
type empty;
}
#includeEtc "caseDicts/setConstraintTypes"
}
// ************************************************************************* //[
0/T
Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Tinlet 255.6;
dimensions [0 0 0 1 0 0 0];
internalField uniform $Tinlet;
boundaryField
{
farfield
{
type inletOutlet;
inletValue uniform $Tinlet;
value $inletValue;
}
airfoil
{
type zeroGradient;
}
frontAndBack
{
type empty;
}
#includeEtc "caseDicts/setConstraintTypes"
}
// ************************************************************************* //
0/Ma
Code:
/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object Ma;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 0 0 0 0 0 0];
internalField uniform 0.72783363;
boundaryField
{
frontAndBack
{
type empty;
}
farfield
{
type calculated;
value uniform 0.72783363;
}
airfoil
{
type calculated;
value nonuniform List<scalar>
279
(
0.72740526
0.72752391
0.72761278
0.72766195
0.72771781
0.72775799
0.72778947
0.72781218
0.72782649
0.72783318
0.727832
0.72782342
0.72780736
0.7277846
0.72775494
0.72771814
0.72767549
0.72762621
0.72757024
0.72750946
0.72744064
0.72736365
0.72728327
0.72719184
0.72708834
0.72698236
0.72686371
0.72672977
0.72659307
0.7264429
0.72627441
0.7261006
0.72591512
0.72571171
0.72549896
0.72527643
0.72503863
0.72478542
0.72452486
0.72426033
0.72398111
0.72368902
0.72341188
0.7231371
0.72283693
0.72255611
0.7222897
0.72199419
0.72171452
0.72145535
0.72117104
0.72089257
0.72063089
0.7203475
0.72006694
0.71980525
0.71952567
0.71924316
0.71897711
0.71869341
0.71840618
0.71813767
0.71784821
0.71755899
0.71729721
0.71701509
0.71673143
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0.71617573
0.71589664
0.71564041
0.71535298
0.71508676
0.71482636
0.71454156
0.714296
0.71403375
0.71376988
0.71352645
0.71325387
0.71300002
0.71272193
0.71245187
0.71219092
0.7119048
0.71162631
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0.71103845
0.71072331
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0.66900423
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0.69293235
0.69935912
0.70393791
0.7074516
0.71018572
0.71241376
0.71427102
0.71582701
0.71716696
0.71831201
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0.72167496
0.72230022
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0.71439189
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0.7203073
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0.72122663
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0.72609275
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0.72729805
0.72701829
0.7266616
0.72623408
0.72574904
0.72520315
0.72461104
)
;
}
}
// ************************************************************************* //
Please feel free to ask for more information if you need them, as I am quite desperate :( |
