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-   -   Setting Pressure on an Outlet Boundary (http://www.cfd-online.com/Forums/cfx/18494-setting-pressure-outlet-boundary.html)

Richard Pemberton April 11, 2001 05:43

Setting Pressure on an Outlet Boundary
 
I'm currently trying to solve a (very simple?) 2 phase problem in CFX. I have a box with the air in the top half and water in the bottom half and there is a flow through the box. I'm trying to set the pressure on the outlet to be hydrostatic in the water part. This is proving to be far more difficult than it should be.

In subroutine USRBCS I use CALL GETVAR('USRBCS','P ',IVAR)

and then after calling subroutine IPREC for the outlet.

VARBCS(IVAR,1,INODE) = RHOW*GRAVITY*(0.52 - ZP(INODE))

where 0.52 - ZP(INODE) is the height term.

I've written data to a file within this routine, I know that the IPREC gets the outlet, I calculate the correct value for pressure, but when I look at the values of P(INODE,1) across the outlet they are all zero. It's confusing me no end, can anyone help?

Gert-Jan van der Gulik April 11, 2001 07:52

Re: Setting Pressure on an Outlet Boundary
 
Have you set IUBCSF correctly?

Gert-Jan

Darcy Jiang April 12, 2001 06:35

Re: Setting Pressure on an Outlet Boundary
 
Richard It is not necessary to use GETVAR because the utility gives you the variable value throughout the computation domain. You can just use the IPREC to get the variable pointer(IPT) on boundaries. These pointer help you get variable location you desired.

ex. P(ipt(i),iphase) = roh * zc(ipt(i))

try it.

Darcy.


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