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-   -   multi- stage-pump: boundary condition (http://www.cfd-online.com/Forums/cfx/20573-multi-stage-pump-boundary-condition.html)

Ben August 20, 2004 05:28

multi- stage-pump: boundary condition
 
Hello,

I have got a problem with setting up the boundary condition of a multi-stage-pump: i want to simulate one stage of a pump by using translational periodic dependencies. my aim is to set up the velocity distribution of the stage-outlet as inlet-boundary condition and also to give the pressure distribution of the stage-outlet reduced by the stage-pressure-rise as inlet condition. to realize this aim i need a 'fortran user source' subroutine. can anybody help me to write this source code or does anybody know where i can get this piece of code. (database, tutorial..)

i hope anybody can help me..

Greets

Ben

Olivier Braun September 1, 2004 09:22

Re: multi- stage-pump: boundary condition
 
Hi Ben,

you do not necessarily need a user fortran code to implement this kind of b.c. You can use a "gravity-like" source term instead of this. Imagine your pump stage working against a (very strong) gravity field only, the axis being vertical. All you have to do is to compute a pressure gradient according to your pressure rise and your axial length (translation vector of your periodicity) and introduce a corresponding momentum source term in axial direction. This should do exactly what you want. In post-processing, you will have to substract the false hydrostatic pressure field you introduced to get the real pressure back (your computed solution will have equal pressure at inlet and outlet).

Hope this helps

Olivier

Ben September 6, 2004 02:15

Re: multi- stage-pump: boundary condition
 
hi olivier

thanks, for your explanation.. your advice solves my problem.

Ben


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