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Poor convergence for Energy e (rhoSimpleFoam, Steady-State) |
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June 26, 2024, 10:05 |
Poor convergence for Energy e (rhoSimpleFoam, Steady-State)
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#1 |
New Member
S03r3n
Join Date: Feb 2024
Posts: 15
Rep Power: 2 |
Hello together,
I have the issue that my simulation (rhoSimpleFoam, steady-state) shows good convergence for velocities U and pressure p but poor convergence for energy e. What can be the reason? Is it solver related? I have attached the convergence plot. Below you can find the thermoType I'm using and the chosen solver settings. thermophysicalProperties Code:
thermoType { type heRhoThermo; mixture pureMixture; transport const; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleInternalEnergy; } mixture { specie { nMoles 1; molWeight 600000; } thermodynamics { Cp 1850; Hf 0; } transport { mu 40000; Pr 370000000; } equationOfState { rho 1154; } } Code:
application rhoSimpleFoam; startFrom startTime; startTime 0; stopAt endTime; endTime 300; deltaT 1; writeControl timeStep; writeInterval 100; purgeWrite 1; writeFormat ascii; writePrecision 6; writeCompression off; timeFormat general; timePrecision 6; runTimeModifiable true; Code:
solvers { p { solver GAMG; tolerance 1e-10; relTol 0.1; smoother GaussSeidel; } "(U|e)" { solver smoothSolver; smoother GaussSeidel; tolerance 1e-10; relTol 0.1; } } SIMPLE { nNonOrthogonalCorrectors 2; } relaxationFactors { fields { p 0.3; rho 0.3; } equations { p 0.3; U 0.7; e 0.7; } } Code:
ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss linearUpwind grad(U); div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear; div(phi,e) bounded Gauss linearUpwind grad(e) div(phid,p) Gauss upwind; div(phi,Ekp) bounded Gauss upwind; div((phi|interpolate(rho)),p) Gauss upwind; } laplacianSchemes { default Gauss linear limited 0.33; } interpolationSchemes { default linear; } snGradSchemes { default limited 0.33; } |
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June 26, 2024, 11:54 |
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#2 |
Senior Member
Join Date: Dec 2021
Posts: 251
Rep Power: 5 |
Hey!
Your thermophysicalProperties values seem weird to me, what kind of fluid has such molecular weight, viscosity and prandtl? Are you sure about these properties? Apart from that, you could maybe add a limiter to the gradient, but everything looks ok to me |
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June 26, 2024, 12:49 |
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#3 | |
New Member
S03r3n
Join Date: Feb 2024
Posts: 15
Rep Power: 2 |
Quote:
Thanks for your message. I try to simulate uncured rubber. Do you have some suggestions? |
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June 28, 2024, 18:57 |
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#4 |
Senior Member
Join Date: Apr 2020
Location: UK
Posts: 742
Rep Power: 14 |
Just reiterating Alczem's earlier post ... lead has a molecular weight of 207 kg/kmol, and you are trying to apply 6x10^5 kg/kmol! Your density is approx the density of lead and your viscosity is off the scale. None of this seems very physical (although I appreciate that uncured rubber might be very viscous).
So again - as per Alczem's post, can I also suggest you check your inputs. |
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July 1, 2024, 10:51 |
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#5 |
New Member
S03r3n
Join Date: Feb 2024
Posts: 15
Rep Power: 2 |
I found out that the convergence behavior of energy e highly depends on Prandtl number, thermal conductivity respectively.
I have changed the transport model to polynomial in order to specify the thermal conductivity (kappa). However, I get bad e-convergence for this case: Code:
transport { muCoeffs<8> ( 15000.0 0 0 0 0 0 0 0 ); kappaCoeffs<8> ( 0.15 0 0 0 0 0 0 0 ); } Code:
transport { muCoeffs<8> ( 15000.0 0 0 0 0 0 0 0 ); kappaCoeffs<8> ( 150 0 0 0 0 0 0 0 ); } Any suggestions? Best regards |
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convergence, energy, openfoam |
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