Fortran code-lattice boltzmann-boundary condition
 

Hi everyone
anybody can help me to write boundary condition fortran code.
I have boundary between cylinder and neighboring lattice point.
http://www.up.lianportal.com/images/...0768462065.jpg

rw is the point at the cylinder surface , rp is the neighboring point inside the cylinder , rl is the neighboring site in the fluid area.
Yu-Mei-Lue-shyy model:
http://www.up.lianportal.com/images/...4188202847.jpg

this method uses following equation:
http://www.up.lianportal.com/images/...4643146862.jpg

Isn't this just a bounce-back boundary condition with interpolation?
Where exactly do you see the problem for the code implementation?

Ah now I think I see: The main problem will be to provide the link information, since you need the populations from neighboring collision sites.
One way to do this is to store the link information (the number of the neighboring site for each link) in a separate field. This way, r_l' can easily be found.

thanks for your reply.
it's easy to store the number of the neighboring sites.

my problem is the delta.http://www.up.lianportal.com/images/...4188202847.jpg

How can I determine it?

This might be done with a little geometry.
Basically, you need to determine the intersection between a straight line (defined by the collision site and the link vector) and a circle (defined by the cylinder).
From the intersection point and the position of the collision site it should be straightforward to determine the cut length Delta.