Boundary Conditions for Inlet, OUtlet and Wall/Turbulence Modeling for flow in pipe
 

Hi Everyone,

I am struggling with the boundary conditions for Inlet/Outlet and Wall for turbulent flow in a pipe using pisoFoam(Parameters- D=0.09m, L=15m, Re=5000) ...I followed the threads which say that the type should be a fixedValue at the Inlet...But still no joy with the simulations....Please help me out..Have been trying to cope with this for the past week....

Regards

Dear Daniel
b.c. for the walls depends on your apporach (high RE or Low Re) which is either wallFunction (for k,Epsilon,R) in High Re or Fixed value (for k&R) (and zero Gradient for Epsilon) in Low Re for turbulent flows. have a look at cfd & turbulent books or search the forum for more info.

If your pipe length is too long you can consider the cyclic B.c.s in inlet&outlet. in this case the channelFoam solver is more suitable because it writes and adds a fixed pressure gradient at each time step. some tools for generating turbulence at inlet had been developed for this case. again search the forums for more info.

But if the length of your pipe is short then the turbulent quantity at the inlet must be specified (k and epsilon) and also the velocity at inlet must be specified.
for outlet zero gradient is a suitable choice for fully developed flow (and of course fixed value for pressure)

You must devote some more time searching in the forum and definitely you can find some more useful threads!

Dear Kia

Thanks a lot for the advice...Will definitely check and get back....

Regards