| Pervispasco |
April 7, 2016 10:42 |
Flow past a 2D cylinder - High Re (1E+05) - Cd too high
1 Attachment(s)
Hi guys,
I am trying to validate Openfoam simulating a 2D flow past a cylinder at high Reynolds Number (Re=1e05 -07), using komega-sst. At the Reynolds number 1E+05 i got pretty good results in term of Cd =1,23 instead of 1,2 and St = 0,23 instead of 0,2. So now i wanted to run the same case at Re = 5E+05. So I modified the mesh in order to get an accurate y+ value (around 30) and the dt to have the Courant number between 0,5 and 1. The problem is that in this case i get a Cd around 0,75 which is too high cause the reference value is around 0,3. And i don't know what am i doing wrong. I'm running K-w SSt model with PisoFoam solver. Maybe i should try running the simulation with the k-Epsilon model?
Here is my setting
-cylinder diameter:2m
-flow velocity:1m/s
-kinematic viscosity:4e-06
-Re=5e05
-y+ max=31.5
-lRef 2 (The diameter of the cylinder)
-Aref 2 (the front area, my cylinder height is 1)
-timestep 0.005s
-simulation time 200s
-my k inlet is calculated as 1.5(UI)^2 U is the flow velocity. I is the turbulence intensity=3,8% = 0,16*Re^(-1/8)
-my omega inlet is calculated as kinlet^0.5/(l*Cmu^0.25) Cmu=0.09 l is the tubulence length l=0.07D
-my initial omega at wall is calculated as omega=10*6v/(beta*deltay^2) v is the kinematic viscosity beta=0.075 deltay is the first boundary layer thickness=0.0012
The flow inlet boundary is located 10D upstream from the centre of the cylinder and the flow outlet boundary is located 30D downstream from the center of the cylinder. The top and bottom boundaries are located at a distance of 10D from the center of the cylinder.
k:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 0.00144;
boundaryField
{
inlet
{
type fixedValue;
value uniform 0.00144;
}
outlet
{
type zeroGradient;
}
top
{
type symmetryPlane;
}
bottom
{
type symmetryPlane;
}
cylinder
{
type kqRWallFunction;
value uniform 0.0;
}
sides
{
type empty;
}
}
// ************************************************************************* //
nut:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -1 0 0 0 0];
internalField uniform 0;
boundaryField
{
inlet
{
type calculated;
value uniform 0;
}
outlet
{
type calculated;
value uniform 0;
}
top
{
type symmetryPlane;
value uniform 0;
}
bottom
{
type symmetryPlane;
value uniform 0;
}
cylinder
{
type nutUSpaldingWallFunction;
value uniform 0;
}
sides
{
type empty;
}
}
// ************************************************************************* //
Omega:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object omega;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 0 -1 0 0 0 0];
internalField uniform 0.496;
boundaryField
{
inlet
{
type fixedValue;
value uniform 0.496;
}
outlet
{
type zeroGradient;
}
top
{
type symmetryPlane;
}
bottom
{
type symmetryPlane;
}
cylinder
{
type omegaWallFunction;
value uniform 4.39e02;
}
sides
{
type empty;
}
}
// ************************************************************************* //
p:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{
inlet
{
type zeroGradient;
}
outlet
{
type fixedValue;
value uniform 0;
}
top
{
type symmetryPlane;
}
bottom
{
type symmetryPlane;
}
cylinder
{
type zeroGradient;
}
sides
{
type empty;
}
}
// ************************************************************************* //
U:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
inlet
{
type fixedValue;
value uniform (1 0 0);
}
outlet
{
type zeroGradient;
}
top
{
type symmetryPlane;
}
bottom
{
type symmetryPlane;
}
cylinder
{
type fixedValue;
value uniform (0 0 0);
}
sides
{
type empty;
}
}
// ************************************************************************* //
fvSchemes:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
ddtSchemes
{
default Euler;
}
gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}
divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
div(phi,k) Gauss limitedLinear 1;
div(phi,omega) Gauss limitedLinear 1;
div(phi,epsilon) Gauss limitedLinear 1;
div(phi,R) Gauss limitedLinear 1;
div(R) Gauss linear;
div(phi,nuTilda) Gauss limitedLinear 1;
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}
laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DomegaEff,omega) Gauss linear corrected;
laplacian(DepsilonEff,epsilon) Gauss linear corrected;
laplacian(DREff,R) Gauss linear corrected;
laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}
interpolationSchemes
{
default linear;
interpolate(U) linear;
}
snGradSchemes
{
default corrected;
}
fluxRequired
{
default no;
p ;
}
wallDist
{
method meshWave;
}
// ************************************************************************* //
fvSolution:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
p
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
}
pFinal
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
}
U
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0;
}
k
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0;
}
omega
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0;
}
epsilon
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0;
}
R
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0;
}
nuTilda
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0;
}
}
PISO
{
nCorrectors 2;
nNonOrthogonalCorrectors 3;
pRefCell 0;
pRefValue 0;
}
// ************************************************************************* //
And here is a picture of the mesh:
Attachment 46547 |
