# Multispecies jet flow in a garage, HELP !!

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 May 25, 2010, 04:36 Multispecies jet flow in a garage, HELP !! #1 New Member   Join Date: Apr 2010 Posts: 5 Rep Power: 9 Sponsored Links 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 !!

 May 27, 2010, 11:04 #2 Senior Member   Eelco van Vliet Join Date: Mar 2009 Location: The Netherlands Posts: 123 Rep Power: 11 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) Code: ```{ volScalarField kappaEff ( "kappaEff", turbulence->nu()/Pr + turbulence->nut()/Prt ); fvScalarMatrix AEqn ( fvm::ddt(A) + fvm::div(phi, A) - fvm::laplacian(kappaEff, A) ); AEqn.relax(); AEqn.solve(); rhok = (rho_air-rho_hel)/rho_air*A;``` and to solve U Code: ``` fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) + turbulence->divDevReff(U) ); UEqn.relax(); if (momentumPredictor) { solve ( UEqn == fvc::reconstruct ( ( fvc::interpolate(rhok)*(g & mesh.Sf()) - fvc::snGrad(p)*mesh.magSf() ) ) ); }```

 May 27, 2010, 14:08 #3 Senior Member   Pei-Ying Hsieh Join Date: Mar 2009 Posts: 314 Rep Power: 11 Hi, Have you looked into twoLiquidMixingFoam? Pei

 May 28, 2010, 10:33 #4 New Member   Join Date: Apr 2010 Posts: 5 Rep Power: 9 Hi, I am actually trying with twoLiquidMixingFoam, I am waiting for the results. Thanks for the advices Eelco, I wil try this way too! Pierre

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