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Boundary conditions for p_rgh

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Old   June 17, 2020, 09:34
Default Boundary conditions for p_rgh
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Nikhil
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Hallo,

I am trying to simulate a leak inside a box. The leaking gas is propane. I am using rhoReatingBuoyantsolver for this. The box, has 2 big outlets, so after 15 seconds(approx.) box starts to fill out and the gas is supposed to go out. But instead of that, box keeps on filling & outlets are acting like walls. It seems, Something is wrong with the pressure boundary conditions of outlet, in particularly with p_rgh. you can see in the figures uploaded, velocity vectors are going parallel to outlet. And i am using janaf thermophysical model. Please, have a look at the attachments and Suggest me something.

https://www.dropbox.com/s/q573kc3gql...domain.7z?dl=0
Code:
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 101325;

boundaryField
{
    leak
    {
        type            calculated;
        value           $internalField;
    }
    outlet
    {
        type            calculated;
        value           $internalField;
    }
   walls
    {
        type            calculated;
        value           $internalField;
    }
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 101325;

boundaryField
{ 
    leak
    {
        type            zeroGradient; //fixedFluxPressure; 
    }
    outlet
    {
	type          totalPressure;
	p0		$internalField;
	U		U;
	phi		phi;
	rho		rho;
	psi		none;
	gamma	0;
        value        $internalField;

	/*type	fixedValue;
      value uniform 101325;*/         	
    }
  walls
    {
        type            fixedFluxPressure;
        value           $internalField;
    }
}


// ************************************************************************* //
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    location    "0";
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    leak
	{
        type            flowRateInletVelocity;
        massFlowRate    constant 0.0005;// Volumetric/mass flow rate [m3/s or 
                                                                                                   // kg/s]
        rhoInlet        1.841; //@20C  
	value       	uniform (0 0 0); // placeholder
	}
    outlet
    {
        type            pressureInletOutletVelocity;
        value           $internalField;
	phi		   phi;
    }
  walls
    {
        type            fixedValue;
        value           uniform (0 0 0); //no slip
    }
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      thermophysicalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
thermoType
{
   type	       heRhoThermo;
   mixture         multiComponentMixture; //reactingMixture;
   transport       sutherland; //const
   thermo          janaf; //hConst
   equationOfState perfectGas;
   energy          sensibleEnthalpy;
   specie          specie;
}

inertSpecie C3H8 air; 
species
( 
C3H8
air
);

C3H8
{
    specie
    {
        molWeight       44.09721;
    }
    thermodynamics
    {
        Tlow            250;
        Tcommon         1000;
        highCpCoeffs    ( 7.5341368 0.018872239 -6.2718491e-06 9.1475649e-10 -4.7838069e-14 -16467.516 -17.892349 );										
        lowCpCoeffs     ( 0.93355381 0.026424579 6.1059727e-06 -2.1977499e-08 9.5149253e-12 -13958.52 19.201691 );
    }
    transport
    {
        As              1.512e-06;
        Ts              120;
    }
    elements
    {
        C               3;
        H               8;
    }
}
air
{
    specie
    {
        nMoles          1;
        molWeight       28.9596;
    }
    thermodynamics
    {
        Tlow            200;
        Thigh           3500;
        Tcommon         1000;
        highCpCoeffs    ( 3.57304 -7.24383e-04 1.67022e-06 -1.26501e-10 -4.20580e-13 -1047.41 3.12431 );
        lowCpCoeffs     ( 3.09589 1.22835e-03 -4.14267e-07 6.56910e-11 -3.87021e-15 -983.191 5.34161 );
    }
    transport
    {
        As              1.67212e-06;
        Ts              170.672;
    }
}
Attached Images
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File Type: jpg post.JPG (75.0 KB, 7 views)
File Type: jpg post_3.jpg (57.4 KB, 7 views)
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Old   June 19, 2020, 20:10
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Lisandro Maders
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Right down your post there are 2 posts which look like had a discussion about BC for p_rgh:

Correct boundary conditions for p_rgh (special for vertical patches)

Common setup for p_rgh in complete open domains

Hope you can find your answer on it!
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Old   June 21, 2020, 13:17
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Nikhil
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Hai Lisandro,

I have seen their posts already and tried with similar boundary conditions. But it isn't working in my case. Anyway thanks for the suggestion. I am working on it, I hope i will find an answer soon.

Cheers,
Nikhil.
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