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Issues on modelling of isotropic part of Reynolds (SGS) stresses |
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February 4, 2015, 04:11 |
Issues on modelling of isotropic part of Reynolds (SGS) stresses
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#1 |
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Hi Foamers,
Recently I am confused about the modelling of Reynolds or SGS stresses in openFoam. Specifically, I don't understand how the isotropic part the the SGS stresses have been considered. According to the turbulent viscosity assumption, the Reynolds or SGS stresses where is deviatoric part of the local strain rate tensor. As discussed in http://www.cfd-online.com/Forums/ope...sonicfoam.html and http://www.cfd-online.com/Forums/openfoam-solving/58214-calculating-divdevreff.html#post388688, , the isotropic part of Reynolds (SGS) stresses, or , are not included in the term of UEqn Code:
fvVectorMatrix UEqn ( fvm::ddt(rho, U) + fvm::div(phi, U) + turbulence->divDevRhoReff(U) ); In many literature, including the book of Pope, it says that this term is absorbed into a modified pressure which leads to the following modelled momentum equation: It is clear that if the turbulent (SGS) kinetic energy is much smaller than the thermodynamic pressure , this term is indeed negligible. So my questions are: 1. Is it true that the term has been neglected in OpenFoam? If this is true, the pressure (in compressible part) is the real pressure, right? 2. How this term can be included, since we already have the value for ? Any idea will be appreciated. Best, Likun |
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June 25, 2015, 05:57 |
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#2 |
Senior Member
Timofey Mukha
Join Date: Mar 2012
Location: Stockholm, Sweden
Posts: 119
Rep Power: 14 |
Realized that this issue is not really clear to me either . Any answers since 2013?
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January 25, 2016, 02:51 |
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#3 |
Member
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New discussions on this issue can find here: http://www.cfd-online.com/Forums/ope...tml#post582044
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