I am trying to change a periodic boundary condition of a LBM code in Matlab to a boundary condition that let me choose the inlet speed flow. I defined the inlet speed, but I see that this is not enough, because the results shows a two convergent flows. If anyone could give me some ideas how may I do it I´ll be thankfull.
I don’t know if I understood your doubt but in fact what you want to do is to specify a velocity BC, isn’t it?
You can follow the traditional procedure of “Zou, Q. and X. He, 1997, On pressure and velocity boundary conditions for the lattice Boltzmann BGK model, Phys. Fluids 9, 1591-1598”: http://pof.aip.org/resource/1/phfle6/v9/i6/p1591_s1?isAuthorized=no
This phorum also contains several posts discussing this particular BC model. I suggest you to give a quick search here…
One last thing, you user_name caught my attention. Are you portuguese?