Hello,

I’m quite new to lattice boltzmann and have some trouble to implement the He/Zou boundary condition for a moving wall. In my case there are two parallel walls of which one has a velocity in x-direction. Now I have somehow managed to implement He/Zou and the results are qualitativly right but 3 times too high. Following is the Fortran-Code for Zou/He, which I implemented between propagation and collision-step:

do x=1,nx

do z=1,nz

density_temp = ftemp(0,x,z) + ftemp(1,x,z) + ftemp(3,x,z) + 2.d0 *(ftemp(4,x,z) + ftemp(7,x,z) + ftemp(8,x,z))

f(2,x,z) = ftemp(4,x,z)

f(5,x,z) = ftemp(7,x,z) - 1.d0/2.d0 * (ftemp(1,x,z) - ftemp(3,x,z)) + 1.d0/2.d0 * u_wu_x * density_temp

f(6,x,z) = ftemp(8,x,z) + 1.d0/2.d0 * (ftemp(1,x,z) - ftemp(3,x,z)) - 1.d0/2.d0 * u_wu_x * density_temp

end do

end do

This code is just applied to the lower wall. I also have to mention, that the collision step is just applied to the fluid and not to the wall. I already tried to change that, but the results were worse.

I’m stuck now and appreciate every hint or help.

Thanks in advance.