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Drag coefficient for a sphere

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Old   July 5, 2011, 13:21
Default Drag coefficient for a sphere
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Join Date: Apr 2011
Location: Magdeburg, Germany
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Nico A. is on a distinguished road
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
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