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what is the meaning of p_rgh?

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Old   September 23, 2016, 10:36
Default what is the meaning of p_rgh?
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Simone Colucci
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I have a simple question. In many solvers (for example in reactingTwoPhaseEulerFoam, OpenFoam 4.0) the PEqn solves an equation for p_rgh, instead of p. p_rgh is defined as:
p_rgh = p - rho*gh;
where :
volScalarField gh("gh", (g & mesh.C()) - ghRef);
If I consider, for example, a vertical pipe with the z_bottom (vertical coordinate)=-10 and the z_top=0, rho*g*h has a physical meaning, but if the coordinates are z_bottom = 0 and z_top = 10, what does it mean?

Thank you in advance

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Old   September 26, 2016, 12:45
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Hasan Celik
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Can you clarify your point little bit more? I mean, I guess h is the difference in height in both cases you mentioned, so isn't it 10?
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Old   September 26, 2016, 22:15
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Pablo Higuera
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Hi Simone,

the truth is that it has no physical meaning, it is just a convenient mathematical artifact. It is explained in my thesis (page 111):


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