[fattah2110]

Hello I just used openfoam to simulate 2 heat sources with 1 fin and also air ducts with "chtMultiRegionFoam" simulation but there is always a fattal error: negative initial temperature T0: -307.56 as I have attached, please help me to solve this problem, thank you very much.



Solving for fluid region fluid
DILUPBiCGStab: Solving for Ux, Initial residual = 0.861158, Final residual = 7.41943e-08, No Iterations 3
DILUPBiCGStab: Solving for Uy, Initial residual = 0.482332, Final residual = 3.06308e-08, No Iterations 3
DILUPBiCGStab: Solving for Uz, Initial residual = 0.517279, Final residual = 2.47086e-08, No Iterations 3
DILUPBiCGStab: Solving for h, Initial residual = 0.896312, Final residual = 3.01582e-08, No Iterations 7
Min/max T:-307.56 758.467
GAMG: Solving for p_rgh, Initial residual = 0.049043, Final residual = 0.000457518, No Iterations 3
GAMG: Solving for p_rgh, Initial residual = 0.0531826, Final residual = 0.000423879, No Iterations 3
GAMG: Solving for p_rgh, Initial residual = 0.0333591, Final residual = 7.1701e-08, No Iterations 20
time step continuity errors : sum local = 4.28568e+08, global = -1.71526e+07, cumulative = -1.71526e+07
Min/max rho:1.196 1.196

Solving for solid region heater1
GAMG: Solving for h, Initial residual = 0.78903, Final residual = 6.75112e-07, No Iterations 9
Min/max T:370.469 389.851

Solving for solid region heater2
GAMG: Solving for h, Initial residual = 0.858166, Final residual = 4.18087e-07, No Iterations 9
Min/max T:359.635 376.68

Solving for solid region fins
GAMG: Solving for h, Initial residual = 0.899828, Final residual = 9.26947e-07, No Iterations 29
Min/max T:283.149 473.151
ExecutionTime = 440.6 s ClockTime = 442 s

volFieldValue volAvgFinTemperature write:
volAverage() of T = 417.445

volFieldValue volAvgHeater1Temperature write:
volAverage() of T = 381.695

volFieldValue volAvgHeater2Temperature write:
volAverage() of T = 370.382

surfaceFieldValue averageTempHeater1FinInterface write:
areaAverage(heater1_to_fins) of T = 382.572

surfaceFieldValue averageTempHeater2FinInterface write:
areaAverage(heater2_to_fins) of T = 372.231

Region: fluid Courant Number mean: 4.66366e+13 max: 7.89855e+16
Region: heater1 Diffusion Number mean: 2.84429e+09 max: 2.86588e+10
Region: heater2 Diffusion Number mean: 3.06795e+09 max: 3.46375e+10
Region: fins Diffusion Number mean: 6.30975e+07 max: 1.56533e+09
Time = 54


Solving for fluid region fluid
DILUPBiCGStab: Solving for Ux, Initial residual = 0.765781, Final residual = 4.85981e-08, No Iterations 3
DILUPBiCGStab: Solving for Uy, Initial residual = 0.328549, Final residual = 2.75657e-08, No Iterations 3
DILUPBiCGStab: Solving for Uz, Initial residual = 0.312839, Final residual = 6.17003e-08, No Iterations 3
DILUPBiCGStab: Solving for h, Initial residual = 0.825268, Final residual = 2.87913e-08, No Iterations 7


--> FOAM FATAL ERROR:
Negative initial temperature T0: -307.56

From function Foam::scalar Foam::species::thermo<Thermo, Type>::T(Foam::scalar, Foam::scalar, Foam::scalar, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar) const, bool) const [with Thermo = Foam::hConstThermo<Foam::rhoConst<Foam::specie> >; Type = Foam::sensibleEnthalpy; Foam::scalar = double; Foam::species::thermo<Thermo, Type> = Foam::species::thermo<Foam::hConstThermo<Foam::rho Const<Foam::specie> >, Foam::sensibleEnthalpy>]
in file /home/torasia/OpenFOAM/OpenFOAM-7/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 56.

FOAM aborting

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::error::abort() at ??:?
#2 Foam::species::thermo<Foam::hConstThermo<Foam::rho Const<Foam::specie> >, Foam::sensibleEnthalpy>::T(double, double, double, double (Foam::species::thermo<Foam::hConstThermo<Foam::rh oConst<Foam::specie> >, Foam::sensibleEnthalpy>::*)(double, double) const, double (Foam::species::thermo<Foam::hConstThermo<Foam::rh oConst<Foam::specie> >, Foam::sensibleEnthalpy>::*)(double, double) const, double (Foam::species::thermo<Foam::hConstThermo<Foam::rh oConst<Foam::specie> >, Foam::sensibleEnthalpy>::*)(double) const, bool) const at ??:?
#3 Foam::heRhoThermo<Foam::rhoReactionThermo, Foam::SpecieMixture<Foam::singleComponentMixture<F oam::constTransport<Foam::species::thermo<Foam::hC onstThermo<Foam::rhoConst<Foam::specie> >, Foam::sensibleEnthalpy> > > > >::calculate() at ??:?
#4 Foam::heRhoThermo<Foam::rhoReactionThermo, Foam::SpecieMixture<Foam::singleComponentMixture<F oam::constTransport<Foam::species::thermo<Foam::hC onstThermo<Foam::rhoConst<Foam::specie> >, Foam::sensibleEnthalpy> > > > >::correct() at ??:?
#5 ? in "/home/torasia/OpenFOAM/OpenFOAM-7/platforms/linux64GccDPInt64Opt/bin/chtMultiRegionFoam"
#6 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#7 ? in "/home/torasia/OpenFOAM/OpenFOAM-7/platforms/linux64GccDPInt64Opt/bin/chtMultiRegionFoam"
Aborted

[Shaowu]

Hi，I also have this problem. There is an issue with the quality of your mesh. You should check if your mesh complies with the gradient consistency principle. In areas with significant changes in physical quantities, the mesh size should be consistent or the mesh specifications should change in a certain direction. Mesh density oscillations are not allowed.