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Equation discretisation in icoFoam

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Old   February 9, 2008, 15:18
Default Hello, looking at the icoFo
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kar
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Kārlis Repsons
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Hello,

looking at the icoFoam solver code, I don't understand how U*(div(U)) is represented by fvm::div(phi,U). Could you please explain?

k.
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Old   February 10, 2008, 01:48
Default Hello Karlis, If you ta
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Michael Jaworski
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Hello Karlis,

If you take a look in the Programmers guide, page P-38 discusses the way OpenFOAM discretises the convection term. In addition, Table 2-2 a couple pages above that tells you that when you write out the convective derivative this way: div(phi, U), that the first field (phi) has to be a surface scalar field. So, during the initiation of the PISO loops, I believe, this phi surface scalar field is created which represents the divergence of the velocity field.

I hope that helps.

Regards,
Mike J.

P.S. The programmers guide can be downloaded from the "documentation" section of the OpenCFD website.
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Old   February 10, 2008, 06:12
Default Hello, My question was wron
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Kārlis Repsons
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Hello,

My question was wrong - div(Ui*U), i = 1,2,3 is represented by fvm::div(phi,U). I would think, flux phi is used later to avoid volume integration, so I still don't understand this one..

Looking at ProgrammersGuide p. 38, equation 2.16 - why is Sf&(ro*U)_f just rewrited as "F"? I think is should be interpolated and integrated somehow.

Also from which time step U values are taken? I guess old one, else, how fvMatrix could be solved..
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Old   February 10, 2008, 07:34
Default Why don't you just take a look
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Why don't you just take a look at my Thesis - it goes through it step by step.

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