# energy equation problem

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 January 12, 2015, 03:12 energy equation problem #1 New Member   Join Date: Jan 2015 Posts: 12 Rep Power: 2 hello, eveybody i'm a new in learning OpenFoam and have problems in reading the EEqn.H in the solver of buyoantSimpleFoam. what do the follwing secentences respect for? he.name() == "e" ? fvc::div(phi, volScalarField("Ekp", 0.5*magSqr(U) + p/rho)) : fvc::div(phi, volScalarField("K", 0.5*magSqr(U))) and i also doubt about the "fvOptions" followed.

January 12, 2015, 04:17
#2
Senior Member

Fabian Roesler
Join Date: Mar 2009
Posts: 185
Rep Power: 8
Hi Gary

Quote:
 he.name() == "e" ? fvc::div(phi, volScalarField("Ekp", 0.5*magSqr(U) + p/rho)) : fvc::div(phi, volScalarField("K", 0.5*magSqr(U)))
is an if structure to decide whether to use
internal energy
Code:
`fvc::div(phi, volScalarField("Ekp", 0.5*magSqr(U) + p/rho))`
or enthalpy
Code:
`fvc::div(phi, volScalarField("K", 0.5*magSqr(U)))`
formulation, where 0.5*magSqr(U) is specific kinetic energy and p/rho should be a work term.

Quote:
 + fvOptions(rho, he)
fvOptions is a kind of library where options like porous media, SRF/MRF and sources for all solvers are implemented. So if you choose to add a source term for a specific cell zone, this will be handled here.

Hope this helps a bit.

Cheers

Fabian

 January 12, 2015, 08:55 #3 New Member   Join Date: Jan 2015 Posts: 12 Rep Power: 2 Thank you very much, Febian. Now i can completely understand it Regard, Gary

January 29, 2015, 04:52
#4
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Join Date: Jan 2015
Posts: 12
Rep Power: 2
Quote:
 Originally Posted by fabian_roesler fvOptions is a kind of library where options like porous media, SRF/MRF and sources for all solvers are implemented. So if you choose to add a source term for a specific cell zone, this will be handled here.
Hi, Fabian

Now i want to add a source term in the energy equation using the fvOptions. where can i get enough info about it?

Regards!

Gary

 February 20, 2015, 05:36 #5 Senior Member     Fabian Roesler Join Date: Mar 2009 Location: Bad Friedrichshall, Germany Posts: 185 Rep Power: 8 Browse the tutorials and you will find everthing you need: Code: ``` energySource1 { type scalarSemiImplicitSource; active true; timeStart 0.2; duration 2.0; selectionMode points; points ( (2.75 0.5 0) ); scalarSemiImplicitSourceCoeffs { volumeMode absolute; injectionRateSuSp { h (10 0); } } }``` Code: ``` source1 { type fixedTemperatureConstraint; active true; timeStart 0.1; duration 0.4; selectionMode cellSet; cellSet ignitionCells; fixedTemperatureConstraintCoeffs { mode uniform; temperature 2000; } }```

 August 7, 2015, 07:55 What "ekp" stands for in EEqn.h file in rhoPorousSimpleFoam #6 New Member   Umesh Join Date: Feb 2015 Posts: 5 Rep Power: 2 Hello Everybody, I am trying to understand a rhoPorousSimpleFoam solver but stuck in the file EEqn.h at solvers directory. fvScalarMatrix EEqn ( fvm::div(phi, he) + ( he.name() == "e" ? fvc::div(phi, volScalarField("Ekp", 0.5*magSqr(U) + p/rho)) : fvc::div(phi, volScalarField("K", 0.5*magSqr(U))) ) - fvm::laplacian(turbulence->alphaEff(), he) == fvOptions(rho, he) ); In above code what is "Ekp" and "K" stands for . And one more question, how to get value in "fvOptions(rho, he)". Thanks in advance. Waiting for your reply.

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