Hello Everybody!!, I am a new users of CFX. Now I would like to simulate gaseous continumm flow in a microchannel(1.2 micron by 3000 micron).We know Knudsen Number Kn <0.001 for continumm flow; 0.001<Kn<0.1 for slip flow and 0.1<Kn<10 for transition flow. Also I need to use slip condition on walls(top and bottom). In case of noslip condition the velocity on the wall is u = 0 but for slip flow velocity on the wall is u = kn*(delu/deln), where kn=lamda/H, is the knudsen number. H is the height of the channel,Lamda is the mean free path, n is the normal coordinate pointing inward from the channel wall. Is it work if write(delu/deln) in CEL of CFX? Please give me informations how can I do it.

Yours Truly Sohag Korea

Sorry my previous problem is not complete.I want to use Knudsen Number Kn <0.001 for continumm flow, 0.001<kn<0.1 for slip flow and 0.1<Kn<10 for transition flow.Also for slip flow velocity on the wall is u=kn*(delu/deln), where kn=lamda/H is the knudsen number,H is the height of the channel,lamda is the mean free path and n is the normal coordinate pointing inward from the channel wall.So How can I use this conditions.Is it possible to write slip condition in CEL of CFX? How can I write (delu/deln)in CEL expressions? I am very grateful to him if any body help me about my problem. Yours Truly Sohag

what is the problem I do not know.I sens full problems but only 1 or 2 line have shown.