| Nico A. |
July 5, 2011 12:21 |
Drag coefficient for a sphere
Hello to all,
I am doing simulations on a sphere at high Re ( 1*e5 - 1*e7 ) using the k-omega-SST turbulence model. Unfortunatly I got the same drag coefficient (Cd) for the different Re and also flow behavior looks the same.
Code:
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
application simpleFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 1200;
deltaT 1;
writeControl timeStep;
writeInterval 50;
purgeWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression uncompressed;
timeFormat general;
timePrecision 6;
runTimeModifiable yes;
functions
{
forces
{
type forces;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 1;
patches
(
sphere
);
rhoName rhoInf;
log true;
rhoInf 1.2041;
CofR ( 0 0 0 );
}
forcesCoeffs
{
type forceCoeffs;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 1;
patches
(
sphere
);
rhoName rhoInf;
log true;
rhoInf 1.2041;
CofR ( 0 0 0 );
liftDir ( 0 1 0 );
dragDir ( 1 0 0 );
pitchAxis ( 0 0 0 );
magUInf 15;
lRef 0.4;
Aref 0.125662;
}
}
I allways adjusted the values for k and omega the different velocities at the inlet (and also at the sphere/wall). I am not sure which values can be changed and which must not be changed. Does anyone have some advices?
Best regards Nico |
