Dear all:

I have some problem in boundary condition.

The Neumann BC for pressure is

partial P / partial n = 0;

In BC, if the flow direction is X-axis, I set

P(x,0)=P(x,1); Am I right?

Dear Ricklee,

If you are having flow in x-direction in a 2D domain, then for the inlet/outlet (say) which are aligned along y-axis, the normal is in x. Thus , dp/dn reduces to dp/dx and hnce po=p1 as you have got. Excuse fot the total derivative symbols. The BC is primarily a simple extrapolation BC when applied to the outlet to first order accuracy. May be more information about the problem you are solving and the specific trouble you are facing could make things clearer.

Hope this helps

Regards,

Ganesh