slip flow in microchannel
Dear sir:
I try to simulate the compressible microchannel flow ( rectangle ). The proposed model assumes the fluid is a continuum but employs a slip velocity boundary condition on the channel wall. slip wall bc: Uwall=Kn*(dU/dy)wall My question is, What kind of Kn I should use, mean value of a cross section or not? Thank you for your help. best regard Sander Nagoo 
Re: slip flow in microchannel
Kn is not it dimensionless number that you calculate from the flow parameters like Re??

Re: slip flow in microchannel
Dear Abeer:
Thank you for your help. But I still don't fully understand. If I want to calculate the wall velocity, should I use mean value of a corss section. Best regard Sander Nagoo 
Re: slip flow in microchannel
If you are doing this in 2D then you would not require to take the mean value, it can be calculated by solving for u(gas)u(wall)= Kn*(du/dy), although i think that this is not the complete equation.

Re: slip flow in microchannel
Dear Raju:
Thank you for your help. I try to compute slip wall velocity according your way(channel flow,length=3000*10^6 m,height=1.2*10^6 m). But I still have two questions about slip velocity. 1)dU/dy is too large, about 10^7. 2)kn=mu*sqrt(pi)/sqrt(2*rho^2*R*T),(mu=1.85*10^5,rho=1.078,R=296.7,T=314) is too small( knout=0.055). The slip wall velocity ( kn*dU/dy ) seems too large.What can I do about this problem? Thank you for your help. Best regard Sander Nagoo 
Re: slip flow in microchannel
the slip wall velocity cannot be that large... think this way,when you have a zero velocity when it is noslip. Then for a small Kn number it should be low. Are you positive that (dU/dy) is so high?

Re: slip flow in microchannel
Dear Raju:
Thank you for your help. Did you ever calculate this problem? Please give me some suggestion. Thank you. Best Regard Sander Nagoo 
All times are GMT 4. The time now is 18:39. 