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-   -   changing the coefficients of pressure correction (https://www.cfd-online.com/Forums/phoenics/52287-changing-coefficients-pressure-correction.html)

 Noel August 1, 2008 11:52

changing the coefficients of pressure correction

Hi all, I need to do some change in IPSA PHOENICS to adjust with my two-phases problem. The source of momentum equation associated with pressure for U_i in PHOENICS is given by r_i*dP, where r_i is the volume fraction of phase-i and dP is the gradient of total pressure.

In my model, the relation between the first and the second phase pressure is expressed by : P1 + P2 = Pc where Pc will be given (a kind of capillary pressure). Therefore, P1 and P2 are not associated with its volume fractions.

I denote dP1, dP2 and dPc as the gradient of P1, P2, and Pc respectively. My plan is to use dP1 as the source of momentum for U_1, while for U_2 the source of momentum will be dPc - dP1 where dPc is given previously. In this way, the pressure correction will work on first phase pressure P1 instead of total pressure P.

To implement this, I will disactivate the term 'built-in source' (in order to cancel the gradient), then I will add dP1 (as source of U_1) and dPc-dP1 (as source of U_2) via GROUND.

I think the problem now is in pressure correction equation whose coefficients, in PHOENICS, has been built-in to accommodate the correction of total pressure in term of r_i*(dP).

Is there a possibility to change this coefficients via GROUND ? If yes, where (which Group) and how (the locations in F-array they are stored) ?

If there is another way which is easier to implement this, I will be pleased and grateful to know that.

Best Regards,

Noel

 9527 April 7, 2009 08:54

HI
i'm very intrested in your problem.i think we need a talk aboat this.
bao_ling2010@hotmail.com

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