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June 17, 2020, 09:34 |
Boundary conditions for p_rgh
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#1 |
Member
Nikhil
Join Date: May 2020
Location: Freiburg
Posts: 43
Rep Power: 5 |
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; //@20°C 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; } } |
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June 19, 2020, 20:10 |
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#2 |
Member
Lisandro Maders
Join Date: Feb 2013
Posts: 98
Rep Power: 13 |
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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June 21, 2020, 13:17 |
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#3 |
Member
Nikhil
Join Date: May 2020
Location: Freiburg
Posts: 43
Rep Power: 5 |
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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