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-   -   Having troubles in understanding the correction term in pressure equation (http://www.cfd-online.com/Forums/openfoam/96556-having-troubles-understanding-correction-term-pressure-equation.html)

kaifu January 25, 2012 18:37

Having troubles in understanding the correction term in pressure equation
 
Hi,

I have troubles in understanding the correction term in pressure equation.
For example in buoyantPimpleFoam,
Code:

       
fvScalarMatrix p_rghDDtEqn
(
    fvc::ddt(rho) + psi*correction(fvm::ddt(p_rgh))
  + fvc::div(phi)
);

where does the term psi*correction(fvm::ddt(p_rgh)) come from?
It seems like it origins from the difference between old value and current value of rho. But how about if we write the eqn as
Code:

       
fvScalarMatrix p_rghDDtEqn
(
    fvc::ddt(psi,p)
  + fvc::div(phi)
);

Back to the correction part, why there is no term like
Code:

       
 p_rgh*correction(fvc::ddt(psi))


pfhan October 8, 2012 05:19

Have you solved it?
I'm confused too. It should be related to the material differential of pressure, but I don't know how to get it in this particular form.


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