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Integral Equation to Foam Equation

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Old   October 25, 2011, 15:32
Default Integral Equation to Foam Equation
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Thilo Michels
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Hi Everyone,

can someone please tell me, if I have implemented my equation right? As this is my first task I implement into openFoam, I'm not sure wether there are errors in my code which is running so far, but crashes after some timesteps.

My Equation is:

\frac{\partial}{\partial t}\int f_i d V + \int{f_i \vec U \vec n}dA+\rho\int{U_i \vec U \vec n}dA +\int{p \vec e\cdot \vec n}dA

with f: velocity times density
U: velocity
p: pressure

My OpenFoam code is:

fvVectorMatrix aFEeqn
(
fvm::ddt(aF)
+ fvm::div(ac_phi,aF)
+ rho * fvc::div(ac_phi_2,U)
+ fvc::grad(aP)
);

Thank you very much in advanced,

Thilo

Last edited by Thilo; November 23, 2011 at 05:06. Reason: Equation in latex form
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Old   November 22, 2011, 19:01
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Daniel P. Combest
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You may have answered this already, but to make your question a little clearer...why not write it using latex (Guide: Writing Equations in LaTeX on the CFD Online Forums).

Code:
\oint_{S} \vec{U}\vec{U}\cdot \hat{n}dA
produces

\oint_{S} \vec{U}\vec{U}\cdot \hat{n}dA

see link above for more explanation
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Old   November 24, 2011, 04:17
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What about the pressure equation ?

Indeed, your equation depends on the pressure field. Consequently the pressure must be evaluated elsewhere.

The classical method is to use SIMPLE or PISO algorithms.. (cf simpleFoam or pisoFoam or icoFoam)

regards,
Cyp
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Old   November 24, 2011, 05:53
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Thilo Michels
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Hi Cyp,

thanks for this advice. Indeed there is a pressure and a density equation, which I didn't mention. I was not shure, if I implemented the mentioned equation right and I didn't want to ask for to much help.

Meanwile I solved my problem!

With kind regards,

Thilo
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