I try to simulate flow over a rotating cylinder with GGI, but I still have problems.
For laminar flows, the vortex shedding only depends on 2 parameters:
- Re, the Reynolds number (d being the diameter of the cylinder and U the upstream velocity, Re=d*U/nu...)
- alpha, the dimensionless peripheral velocity (the ratio of the cylinder’s peripheral speed to the speed of the flow, alpha=(d*pi*rpm)/(60*U)...)
I am surprised to get different results when I use the same set of parameters (Re=200 & alpha=1.5) but different values of upstream velocities, of diameters, of rounds per minute.
For example, if instead of (d=0.1 m, U=0.03 m, rpm=8.594368715 rpm), I use (10*d, U/10, rpm/100), flows are far different. But Re and alpha are the same, so results should be the same.
The input files include:
- in 0/U:
value uniform (0.03 0 0); //or 0.03/10=0.003
- in constant/polyMesh/blockMeshDict:
convertToMeters 0.1; //or 0.1*10=1
(0 -0.5 0) //cylinder
(0.5 0 0) //cylinder
(0 0.5 0) //cylinder
(-0.5 0 0) //cylinder
- in constant/dynamicMeshDict:
origin (0 0 0);
axis (0 0 1);
direction (1 0 0);
rpm 8.594368715; //or 0.08594368715
- in system/controlDict:
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 0);
magUInf 0.03; //or 0.003
lRef 0.1; //or 1
Aref 0.01; //or 1
Tell me where I’m wrong! Where could be the mistake? Tell me things I should try to solve this problem...
If you need any further detail, just ask.
Is there a way to check the Reynolds number?
Maybe I am not in the conditions I expect...
I think I study Re=200, but it's perhaps not the case?
I think I have the answer.
I was actually not at the same Reynolds number. Indeed, I made a mistake that hopefully I've solved.
Sorry for making a new thread for nothing...
|All times are GMT -4. The time now is 22:42.|