Hi, I have a 3D case runnin
I have a 3D case running of a sphere(d=1) with Re=50 and I want to determine the drag.
I used the following in my controlDict
functionObjectLibs ("libforces.so"); //Lib to load
patches (sphere_GmshSphere); // change to your patch name
rhoInf 1.22; //Reference density for fluid
CofR (0 0 0); //Origin for moment calculations
patches (sphere_GmshSphere); //change to your patch name
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 0);
nu nu [0 2 -1 0 0 0 0] 1.5e-05;
the problem is now , that my drag is too high(about 7 what should be 1.5).
Can someone see the a mistake or shall I blame the Grid ?
If someone has a case which gives good results for a laminar flow I would be happy about every input.
hi, when did simulation on
when did simulation on an airfoil, i also had too high drag. the distance to toe far boundary edge was 40 times the airfoils chord length. increasing to 100 times the chord length improved it.
--> try make the grid around the sphere very huge!
and yes, the grid is a very sensitive factor to the results. try not to get too great skewness near the boundary layer. and also refine the mesh behind the sphere.
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