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-   -   Free jet simulation (http://www.cfd-online.com/Forums/openfoam/80121-free-jet-simulation.html)

 msarkar September 16, 2010 02:35

Free jet simulation

2 Attachment(s)
Hello Foamers,

I am trying to simulate a heated air jet dispersion in an open area. The heated air is coming out from a pipe leak ( leak diameter 1cm) with a velocity of 135 m/s and a temperature of 100 C. In this case, the Mach-number is around 0.4 which is mildly compressible flow. So, I was using rhoSimpleFoam and rhoPImpleFoam. I tried several boundary conditions and mesh sizes but with out any success. The results do not look reasonable. As initial case I am considering a 2D rectangular geometry. Could you please suggest me which solver I should use?

The mesh and boundary file and one set of used boundary conditions are attached here. If you have any suggestions regarding boundary conditions, Please let me know. Any help would be very much appreciated.

top:
alphat: type calculated

epsilon:
type inletOutlet;
inletValue uniform 0.01;
value uniform 0.01;
k:
{
type inletOutlet;
inletValue uniform 0.1;
value uniform 0.1;
}

mut:
type calculated;

p:
{
type fixedValue;
value uniform 100000;
}

T:
{
value uniform 333;
}

U:
{
type pressureNormalInletOutletVelocity;
//type slip;
phi phi;
rho rho;
value uniform (0 0 0);
}

bottom:
alphat: type calculated

epsilon:
type inletOutlet;
inletValue uniform 0.01;
value uniform 0.01;

k:
{
type inletOutlet;
inletValue uniform 0.1;
value uniform 0.1;
}

mut:
type calculated;

p:
{
type fixedValue;
value uniform 100000;
}

T:
{
value uniform 333;
}

U:
{
type pressureNormalInletOutletVelocity;
//type slip;
phi phi;
rho rho;
value uniform (0 0 0);
}

inlet:
alphat: type calculated

epsilon:
{
type compressible::turbulentMixingLengthDissipationRate Inlet;
mixingLength 0.0005; // 0.01*0.05
value uniform 0.01;
}

k:
{
type turbulentIntensityKineticEnergyInlet;
intensity 0.05;
value uniform 0.1;
}

mut:
type calculated;

p:
{
value uniform 100000;
}

T:
{
type fixedValue;
value uniform 373;
}

U:
{
type fixedValue;
value uniform (135.74 0 0);
}

outlet:
alphat: type calculated

epsilon:
{
type inletOutlet;
inletValue uniform 0.01;
value uniform 0.01;
}

k:
{
type inletOutlet;
inletValue uniform 0.1;
value uniform 0.1;
}

mut:
type calculated;

p:
{
type fixedValue;
value uniform 100000;
}

T:
{
value uniform 333;
}

U:
{
type inletOutlet;
phi phi;
rho rho;
value uniform ( 0 0 0 );
inletValue uniform ( 0 0 0 );
}

lowerleft:
alphat:
type alphatWallFunction;
Prt 0.85;
value uniform 0;

epsilon:
{
type compressible::epsilonWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0.01;
}

k:
{
type compressible::kqRWallFunction;
value uniform 0.1;
}

mut:
{
type mutWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0;
}

p:
{
type fixedValue;
value uniform 100000;
}

T:
{
value uniform 333;
}

U:
{
type fixedValue;
value uniform (0 0 0);
}

upperleft:
alphat:
type alphatWallFunction;
Prt 0.85;
value uniform 0;

epsilon:
{
type compressible::epsilonWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0.01;
}

k:
{
type compressible::kqRWallFunction;
value uniform 0.1;
}

mut:
{
type mutWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0;
}

p:
{
type fixedValue;
value uniform 100000;
}

T:
{
value uniform 333;
}

U:
{
type fixedValue;
value uniform (0 0 0);
}

frontAndBack:

For all variables it is empty.

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