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 ranas July 8, 2009 09:53

flow around 2-Dimension cylinder

Hi,

I am calculating flow around 2-D cylinder at Re=200 with OpenFOAM. The radius of the cylinder is 0.5m. The velocity of incoming flow is 1m/s. Mu equals to 0.005.

The full grid is shown here:

grid

I used the following schemes:
ddtSchemes
{
default CrankNicholson 0.5;
}
{
default Gauss linear;
}
divSchemes
{
default none;
div(phi,U) Gauss linear;
}
laplacianSchemes
{
default none;
laplacian(nu,U) Gauss linear corrected;
laplacian(1|A(U),p) Gauss linear corrected;
}
interpolationSchemes
{
default linear;
interpolate(HbyA) linear;
}
{
default corrected;
}
fluxRequired
{
default no;
p;
}

The standard ICCG and BICCG solvers are used untill convergence to resectively 1e-6 and 1e-5 is obtained. The time step was chosen to be 0.01.

Also the standard boundary conditions are applied:
inlet: U fixed and zeroGradient for p
outlet: p fixed and zeroGradient for U
upper/lower boundary: zeroGradient for p and for U

forceCoeffs
{
type forceCoeffs;
functionObjectLibs ("libforces.so");
patches (circle); //change to your patch name
rhoInf 1;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 0);
magUInf 1;
lRef 1;
Aref 1.0;
}

BrazaM (1985 N um )' result: time average of cd=1. 31; amplitude of cl=0. 65; st=0. 194.
my result: time average of Cd is about 1.9, larger than 1.31; the amplitude of Cl is about 1.0 , more than 0.65; but the st number equals to 0.196 close to the result.

Is someone having any ideas on what's wrong with it? Do I use the proper schemes? Are the bounday conditions correct?

Thanks,
Ranas

 ranas July 9, 2009 03:46

I am calculating flow around 2-D cylinder at Re=200 with OpenFOAM. The radius of the cylinder is 0.5m. The velocity of incoming flow is 1m/s. Mu equals to 0.005.

The full grid is shown here:

grid

I used the following schemes:
ddtSchemes
{
default CrankNicholson 0.5;
}
{
default Gauss linear;
}
divSchemes
{
default none;
div(phi,U) Gauss linear;
}
laplacianSchemes
{
default none;
laplacian(nu,U) Gauss linear corrected;
laplacian(1|A(U),p) Gauss linear corrected;
}
interpolationSchemes
{
default linear;
interpolate(HbyA) linear;
}
{
default corrected;
}
fluxRequired
{
default no;
p;
}

The standard ICCG and BICCG solvers are used untill convergence to resectively 1e-6 and 1e-5 is obtained. The time step was chosen to be 0.01.

Also the standard boundary conditions are applied:
inlet: U fixed and zeroGradient for p
outlet: p fixed and zeroGradient for U
upper/lower boundary: zeroGradient for p and for U

forceCoeffs
{
type forceCoeffs;
functionObjectLibs ("libforces.so");
patches (circle); //change to your patch name
rhoInf 1;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 0);
magUInf 1;
lRef 1;
Aref 1.0;
}

BrazaM (1985 N um )' result: time average of cd=1. 31; amplitude of cl=0. 65; st=0. 194.
my result: time average of Cd is about 1.9, larger than 1.31; the amplitude of Cl is about 1.0 , more than 0.65; but the st number equals to 0.196 close to the result.

Is someone having any ideas on what's wrong with it? Do I use the proper schemes? Are the bounday conditions correct?

Thanks,
Ranas

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