CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM (http://www.cfd-online.com/Forums/openfoam/)
-   -   Multispecies jet flow in a garage, HELP !! (http://www.cfd-online.com/Forums/openfoam/76399-multispecies-jet-flow-garage-help.html)

 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)
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())
)
)
);
}

 phsieh2005 May 27, 2010 14:08

Hi,

Have you looked into twoLiquidMixingFoam?

Pei

 Pierre Mathieu May 28, 2010 10:33

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

 All times are GMT -4. The time now is 01:43.