View Issue Details
ID | Project | Category | View Status | Date Submitted | Last Update |
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0002937 | OpenFOAM | Bug | public | 2018-05-15 15:57 | 2018-05-17 11:18 |
Reporter | lavdwall | Assigned To | henry | ||
Priority | low | Severity | minor | Reproducibility | always |
Status | closed | Resolution | no change required | ||
Product Version | dev | ||||
Fixed in Version | dev | ||||
Summary | 0002937: kinetic theory: granular pressure in (div)DevRhoReff | ||||
Description | Shouldn't there be a granular pressure term in the stress tensor when using the kinetic theory of granular flow? In kineticTheoryModel.C, devRhoReff is defined as follows: - (rho_*nut_) *dev(twoSymm(fvc::grad(U_))) - ((rho_*lambda_)*fvc::div(phi_))*symmTensor::I But according to eqn B1 and B2 in the MFiX documentation (https://mfix.netl.doe.gov/download/mfix/mfix_current_documentation/MFIXEquations2012-1.pdf) the solids stress term should be - (rho_*nut_) *dev(twoSymm(fvc::grad(U_))) - ((rho_*lambda_)*fvc::div(phi_)-psolids)*symmTensor::I with psolids = granularPressureModel_->granularPressureCoeff(alpha,gs0_,rho,e_) * Theta_ | ||||
Tags | No tags attached. | ||||
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I think this has be discussed at length before, take a look through previous posts related to kinetic theory. |
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The granular (and frictional) pressures are separately taken into account in pEqn. For example, in twoPhaseEulerFoam (https://github.com/OpenFOAM/OpenFOAM-dev/blob/master/applications/solvers/multiphase/twoPhaseEulerFoam/pU/pEqn.H) the phase1.turbulence().pPrime() -term adds the effect of the pressure. In reactingEulerFoam it is included in fluid.phiFs. |
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OK, so in theory, if the phase1.turbulence().pPrime() function is set to return a zero field, and the pressure is included in divDevRhoReff instead, it should give the same result? Because if I try that, the bed dynamics are quite different... |
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In theory perhaps, but in practice likely not. One reason for separating the pressure is to avoid checker-boarding effects. It is numerically better to calculate the pressure flux directly at the faces instead of calculating it in divDevRhoReff and then interpolating to faces. Also, the current formulation allows eg. implicitPhasePressure-treatment. |
Date Modified | Username | Field | Change |
---|---|---|---|
2018-05-15 15:57 | lavdwall | New Issue | |
2018-05-15 16:22 | henry | Priority | normal => low |
2018-05-15 16:22 | henry | Severity | major => minor |
2018-05-15 16:22 | henry | Note Added: 0009578 | |
2018-05-16 07:15 | tniemi | Note Added: 0009584 | |
2018-05-16 21:22 | lavdwall | Note Added: 0009588 | |
2018-05-17 08:31 | tniemi | Note Added: 0009589 | |
2018-05-17 11:18 | henry | Assigned To | => henry |
2018-05-17 11:18 | henry | Status | new => closed |
2018-05-17 11:18 | henry | Resolution | open => no change required |
2018-05-17 11:18 | henry | Fixed in Version | => dev |