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Andreas February 24, 2003 05:01

Inlet boundary condition

I want to specify a inlet velocity condition normal to the inlet surface. I couldnīt find a button to do that. Do I have to create a local coordinate system for each inlet surface?

Regards, Andreas

Marc February 24, 2003 12:39

Re: Inlet boundary condition

Josh February 24, 2003 13:57

Re: Inlet boundary condition
What if the surface is curved?

Murali February 24, 2003 14:02

Re: Inlet boundary condition
<font face = "Courier new">I think it can be tackled in a different manner. Instead of making a co-ordinate system for every surface, which may lead to innumerable local systems, one can use the POSDAT to specify the velocities at the first iteration. The way to do is as follows:

(1) change the cell type of the cells attached to the inlet surface.

(2) In POSDAT use this cell type information(ICTID) and with some appropriate STAR common blocks ( e.g. LQ and LX), and obtain the face normal vector of the surface where the velocity boundary condition is to be applied.

(3) Now you have the cell info ( or the spatial info of surface) and the direction info (face normal). All you have to do is multiply appropriate velocity magnitudes for the cells to obtain the velocity vector.You have two options now:

(a)Print out in an orderly fashion the various veloities, cell and boundary info etc.. on a file. Then use the appropriate boundary suboutine to read this information every time during the iteration.

(b)I think POSDAT itself can set the boundary condition if called in the beginning of the iteration. Use level 1 of POSDAT to set this boundary condition everytime you iterate.

(Of course these suggns are a little speculative)


raymond February 24, 2003 21:08

Re: Inlet boundary condition
Why not try the user subroutine "bcdefi"?

CJ Tune February 24, 2003 22:04

Re: Inlet boundary condition
Yes, combine it with Murali's suggestion. Have posdat.f extract the face normal vectors, use that to get the velocity vectors and then share with bcdefi either via 1.) writing and reading from file, or 2.) your own common block. If you include the STAR common block C1C001/ICLMAP(NCTMAX) in bcdefi, maybe you don't need to use posdat.f at all.

You can find out more at

Andreas February 25, 2003 01:34

Re: Inlet boundary condition
Thank you very much. In my current problem are only plane inlet surfaces, so I try to create local coordinate systems at each inlet.

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