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-   -   Multispecies jet flow in a garage, HELP !! (

Pierre Mathieu May 25, 2010 04:36

Multispecies jet flow in a garage, HELP !!
Hi everyone,

I want to simulate the injection of Helium into air in a confined space, and I am quite new with OpenFoam.

I used the reactingFoam solver adding the gravity effect (rho*g) to the velocity equation (UEqn.H) but my results are bad : my species are mixing like if there was no buoyancy effects between them...

I want to figure the density effects between the species during the injection.

If someone have some advices to give, I would be grateful.
Thank you !!

eelcovv May 27, 2010 11:04

Hi Pierre,

Perhaps you can use something simular as buoyantBoussinesqPisoFoam, which means you only solve one phase (air) and solve helium as a passive scalar A mixing into the room with A=1 at inlet and A=0 at t=0 in the room. Solve the transport of A and add a momentum source to your U equation based on the fraction of helium in air (just a the boussinesq equation). Something like below, but I haven't checked it, so probably needs some adjustments. Goodluck

To solve transport of A (helium fraction)

    volScalarField kappaEff
        turbulence->nu()/Pr + turbulence->nut()/Prt

    fvScalarMatrix AEqn
      + fvm::div(phi, A)
      - fvm::laplacian(kappaEff, A)



    rhok = (rho_air-rho_hel)/rho_air*A;

and to solve U


    fvVectorMatrix UEqn
      + fvm::div(phi, U)
      + turbulence->divDevReff(U)


    if (momentumPredictor)
                    fvc::interpolate(rhok)*(g & mesh.Sf())
                  - fvc::snGrad(p)*mesh.magSf()

phsieh2005 May 27, 2010 14:08


Have you looked into twoLiquidMixingFoam?


Pierre Mathieu May 28, 2010 10:33


I am actually trying with twoLiquidMixingFoam, I am waiting for the results.

Thanks for the advices Eelco, I wil try this way too!

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