A small question, I just pe
 

A small question,

I just performed a cylinder flow with icoFoam, but the result seems to be different from those in ferzifer's book. So i am wondering what might be wrong.

How to set upper and lower boudaries conditions?

wall or cyclic, Any ideas? Thanks a lot.

Because I am afraid if I use wall patch when Re is high, the mesh will be very expensive. I saw some paper used cyclic though in fact it is actually another problem.

Daniel

Hi Daniel, This question s
 

Hi Daniel,
This question seems far too general to be answered in any sort of detail. Maybe you could tell us *how* the solution is different and compared to what? An analytical solution? another simulation? experiment?

Also, have you done the potentialFoam tutorial? It's detailed in the Programmer's guide and covers a cylinder in cross-flow. Maybe that would be a good place to start and see how BCs are set there.

Good luck,
Mike J.

I am making my effort to simul
 

I am making my effort to simulate the case cylinder flow as described in "Computational Methods for Fluid Dynamics" Chapter 8, and I hope to get a better understanding of liftDrag (for my ultimate aim to to simulate drag reduction).

The geometry is the same as Ferziger's.
I meshed with gmsh, and then used gmsh2ToFoam.
Re is 20,40,100,150.
fvSolution and fvScheme are the same as those in icoFoam/cavity, and are not changed.
I lowered the 1st cell hight to satisfy y+=1.
The velocity profile, I used both the parabolic one and the uniform one.
One thing I'm not sure is the upper and lower wall boundary condition, which type should I set?

whatever, the variation of CD on a cylinder is very smooth on the book of Ferziger, however, mine is not smooth at all!
http://www.cfd-online.com/OpenFOAM_D...ges/1/6654.gif
meanwhile, the meanvalue is too small.
Here is Prof. Ferziger's
http://www.cfd-online.com/OpenFOAM_D...ges/1/6655.gif

Hi Mike, thank you,
I noticed in potentialFoam tutorial, the BC is symmetryPlane. But how about cyclic? Will the result be of great defference?

I'm still very new to CFD. Co
 

I'm still very new to CFD.
Could anyone point out what's going wrong here, thanks.