Problem with wall function
1 Attachment(s)
Dear Openfoamer.
I am a new in modelling, I want to study turbulence over a plane plate, but now I am dealing a problem with the wall function. Normally i should have a beautiful log law function but I got the following wind profile showed in the following picture. My boundary are as follow Inlet pressure zerogradient U fixed value k fixedvalue epsilon fixedvalue Outlet pressure fixedvalue U zerogradient k zerogradient epsilon zerogradient Wall pressure zerogradient U fixedvalue k kqrwallfunction epsilon epsilonwallfunctionn The case consist of a box inlet is in the left outlet is on the top and on the right wall is on the bottom the case is in 2D. If someone could give me an advice it would be nice Thanks in advance. 
Are the front and back walls with the "empty" boundary condition?
And what is the size of your mesh? Can you post the values of y+ (i think the command is yPlusRas. Standart kepsilon turbulence mode? What about the convergence? Did it pass the 1e5? 
1 Attachment(s)
Hi
The front and back got empty conditions. and yes i use a kepsilon model The profile of yplus is in the atached file. I had done several test with several model, it show that it's the boundary conditions are the problem I tried Pisofoam, simplefoam, with the both condition LES RAS but the given answer is the same. For the convergeance i don't knbow how to get it. I give you a sample of a time step perhaps it s inside. Quote:

Hi,
is the left y axis the y+ value? Try increasing the size of the mesh near the walls and get a value of y+ between 30 and 300, your mesh seems to small for the kepsilon model. 
Hi,
No the wind is on the left the input is an uniform 10m/s wind. on the right is the yplus. I will today increase the mesh size near the wall... I hope it would work. Thanks for the advice 
Hi,
I found that it the wall function or some misunderstood of this experiment because i tried different mesh size, I try the dnsFoam And all give the same answer. So i think the configuration I gave is wrong :confused: If somebody know how to have a beautiful loglaw please tell me... perhaps the input should be a loglaw too? 
All times are GMT 4. The time now is 14:10. 