I am working with rarefied gas microflow in micro channel. Here . To use N-S equation in this area I need to use slip boundary condition. I use Fluent 6.1. I can not create its UDF code. On the tutorial, I haven't found a complete explanation about this kind of UDF. If any one code this slip condition for fluent I will be grateful to him. Tajul

Fluent has a Maxwell slip boundary condition for low pressure gas systems in version 6.2 but i think its in 6.1 as well. Details in section 14.2.2 of the user manual.

The only other way I know off to specify a slip condition in Fluent is to give a constant shear value in the wall boundary conditions.

Hi Thank you for your response. I want to use the wall slip condition

u=constant*(delu/deln), where u is the wall velocity and n is the normal coordinate pointing inward from the channel wall. Tajul