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Error or Different Meaning of alpha in eEqu and hEqu of compressible solver? |
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July 20, 2010, 12:56 |
Error or Different Meaning of alpha in eEqu and hEqu of compressible solver?
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#1 |
New Member
yu
Join Date: Nov 2009
Posts: 26
Rep Power: 17 |
In compressible flow solvers, eEqu and hEqu share the same parameter "thermal diffusivity", or turbulence->alphaEff() in the following equations. However, my understanding of the meaning of thermal diffusivity should be different in these equaitons, i.e. , (for a laminar flow),
In eEqu, alpha = K / (Cv rho), where Cv, k and rho are heat capacity at constant volume, theremal conductivity and density, respectively. while, in hEqu, alpha = k / ( Cp rho), where Cp, k and rho are heat capacity at constant pressure, theremal conductivity and density, respectively. My questions are: 1, my understanding about alpha is right or wrong? 2, if i am right, is openFoam wrong ?, or there is specific application inside openfoam dealing with this issue? ======================================== In sonicFoam eEqu is solve ( fvm::ddt(rho, e) + fvm::div(phi, e) - fvm::laplacian(turbulence->alphaEff(), e) == - p*fvc::div(phi/fvc::interpolate(rho)) ); ======================================== In rhoPisoFoam hEqu is fvScalarMatrix hEqn ( fvm::ddt(rho, h) + fvm::div(phi, h) - fvm::laplacian(turbulence->alphaEff(), h) == DpDt ); Last edited by universez; July 26, 2010 at 14:38. |
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August 8, 2010, 12:51 |
compare with rhoFurbFoam
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#2 |
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Hi yu
you are not wrong in understanding but you have compare similar solvers like rhoTurbFoam in 1.5 and sonicFoam in 1.6. iam working on both the slovers and i feel both are same (Unsteady Turbulent compressible solvers). try to analyze with rhoTurbFoam that will clear your doubt. |
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