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 Pang Shengyong August 14, 2007 15:30

convective boundary condition for outflow BC

Hi, all

I have used the convective BC for outflow condition in my code. However, I am not quite understand that how to set the outflow condition for a variable shear to the outlet.

For instance, for an backstep test, the fluid flow from the left to right, and I set this direction as U(which is normal to the outlet), clearly, the U at outlet can be solved with CBC condition equation,

Un[i] = U[i] - c*(U[i]-U[i-1])*dt/dx , c is some const speed

My question is that how to solve the V and W at the outlet? Use the same way or just set them to zero?

I have also heard that if the Peclet Number is huge, then we need no BC for the outflow, is it right?

regards, shengyong

 pankaj saha August 24, 2007 17:21

Re: convective boundary condition for outflow BC

hi pang,

You must use the same procedure for v and w. Just replace v,w...inplace of u.

thanks.

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