# "Slip Boundary Condition,Help me Please"

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 June 19, 2007, 23:23 "Slip Boundary Condition,Help me Please" #1 Sohag Guest   Posts: n/a I am a new user of CFX. I consider gaseous flow in a 2D microchannel (L=3mm, H =0.0012mm).In this problem I want to use slip boundary conditions: (1) Ug-Uw = Kn*(delU/deln) (2) Tg-Tw = (Kn/Pr)*(delT/deln) where Ug = vel of gas, Uw = vel of wall, Kn = Knudsen number(for slip flow 0.001 < Kn <0.1), n = inward normal direction to the wall, so (delU /deln) and (delT/deln) are the tangential velocity and temperature, Pr = Prandtl number. Are these possible to write using CEL function? But in CEL how (delU/deln) can be written? If not possible then how can I write using FORTRAN subroutine? Please give me directions or give me any sample subroutine that I can write my subroutine. If any one help me I will be grateful to him and appreciate his kindness. Yours Truly Sohag

 June 21, 2007, 06:34 Hi Mr. Opaque and Robin, Plz see my problem!! #2 Sohag Guest   Posts: n/a Dear Opaque and Robin, Both of you are so expert and always try to response to others problems.Would you plz see my problem that I send and give me some instructions that will help me. Yours Truly Sohag