# Declaration of the function TH()

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 August 1, 2012, 17:15 Declaration of the function TH() #1 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,555 Blog Entries: 6 Rep Power: 27 Hi all, I am trying to find the place where the temperature is derived from the enthalpy. - Solver: rhoSimpleFoam - thermodynamics: hPsiThermo - transport: hConstTransport Therefor I had a look at the solver and the enthalpy equation h: Code: ```{ fvScalarMatrix hEqn ( fvm::div(phi, h) - fvm::Sp(fvc::div(phi), h) - fvm::laplacian(turbulence->alphaEff(), h) == - fvc::div(phi, 0.5*magSqr(U), "div(phi,K)") ); hEqn.relax(); hEqn.solve(); thermo.correct();``` Here I think the step I am searching is in the function "correct". That leads me to the thermomodel -> hPsiThermo.C. From the correct() function you get into the calculate() function. And there (I think) you get the temperature derived from the enthalpy. Its described in the *.H file that T is calculated there. I found that function: Code: ` TCells[celli] = mixture_.TH(hCells[celli], TCells[celli]);` And would find the definition of that function. With grep I get into the specieThermo.H file. Here I found that: Code: ``` // Energy->temperature inversion functions //- Temperature from Enthalpy given an initial temperature T0 inline scalar TH(const scalar H, const scalar T0) const;``` So I am very sure that I am on the right way. But thats just a function prototype and not a function declaration. I searched everywhere but do not find the definition of that function. Where can i find it? Can someone give me an advice? Thanks in advance Tobi

 August 1, 2012, 17:30 #2 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,555 Blog Entries: 6 Rep Power: 27 I should have a look at the specieThermoI.H So solved Thanks for reading

 August 1, 2012, 17:50 #3 Senior Member     Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 728 Rep Power: 20 If you look in specieThermoI.H you will find the function TH. Looking at it you will see that the template is calling another function T and feeding it the proper coefficients (whether its enthalpy or energy you are inverting). The function T is also in the file, near the very beginning. Here is where temperature is obtained by inverting the enthalpy/energy based on the the species thermo (its a simple Newton's method if I read the code right). EDIT: Hehe Tobi, you must have been thinking while I was typing ;-) Last edited by mturcios777; August 1, 2012 at 17:51. Reason: Answered already

 August 1, 2012, 17:56 #4 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,555 Blog Entries: 6 Rep Power: 27 Hihi, well, nevertheless thanks for reading and anwering You are right. After I read the specieThermoI.H file I saw that TH is calling a other function T() and thats defined in the beginning of the thermo model Wow .. cool ... hihi. I am getting familiar and familiar with OF code.

August 28, 2013, 03:42
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 Originally Posted by Tobi Hihi, well, nevertheless thanks for reading and anwering You are right. After I read the specieThermoI.H file I saw that TH is calling a other function T() and thats defined in the beginning of the thermo model Wow .. cool ... hihi. I am getting familiar and familiar with OF code.
Hello Tobias and Marcos,

I have this same type of problem but like you I am not a very senior CFD specialist. I was trying to follow your comments but I do not understand how to resolve this issue. I have recently enrolled in postgrad by research student this is my first time with CFD and openfoam. I am solving for air flow in a pipe. Air is taken as compressible. So I am using rhoPimpleFoam. Can you please advise how I can get rid of this error.

I have applied following strategies

1. With small number of cells (coarse mesh), as rhoMax increases, number of time steps increase before solution fails.2. As number of cells increase, as rhoMax increases, number of time steps decrease against the same number of rhoMax.

I have tried this strategy on cell size 13000, 26000 and 85000 for 8 trial cases for rhoMax 2, Pressure 100,000 and Temperature 300.

I have tried to increase pressure and temperatures also.

Upon increasing value of pressure to 200,000, error was produced at 0.0184 against 0.0181 at 100,000. The error came after only three more steps. Cell number is 13000. Value of rhoMax was kept as 2.

Upon increasing the value of temperature to 400, error was produced at 0.0458 against 0.0341 at 300. Cell number is 13000. Value of rhoMax was kept as 2.

I shall be very grateful.

Regards

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 error.jpg (57.5 KB, 50 views)

August 28, 2013, 03:43
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Quote:
 Originally Posted by Tobi Hihi, well, nevertheless thanks for reading and anwering You are right. After I read the specieThermoI.H file I saw that TH is calling a other function T() and thats defined in the beginning of the thermo model Wow .. cool ... hihi. I am getting familiar and familiar with OF code.
Hello Tobias and Marcos,

I have this same type of problem but like you I am not a very senior CFD specialist. I was trying to follow your comments but I do not understand how to resolve this issue. I have recently enrolled in postgrad by research student this is my first time with CFD and openfoam. I am solving for air flow in a pipe. Air is taken as compressible. So I am using rhoPimpleFoam. Can you please advise how I can get rid of this error.

I have applied following strategies

1. With small number of cells (coarse mesh), as rhoMax increases, number of time steps increase before solution fails.

2. As number of cells increase, as rhoMax increases, number of time steps decrease against the same number of rhoMax.

I have tried this strategy on cell size 13000, 26000 and 85000 for 8 trial cases for rhoMax 2, Pressure 100,000 and Temperature 300.

I have tried to increase pressure and temperatures also.

Upon increasing value of pressure to 200,000, error was produced at 0.0184 against 0.0181 at 100,000. The error came after only three more steps. Cell number is 13000. Value of rhoMax was kept as 2.

Upon increasing the value of temperature to 400, error was produced at 0.0458 against 0.0341 at 300. Cell number is 13000. Value of rhoMax was kept as 2.

I shall be very grateful.

Regards

August 28, 2013, 03:44
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starter
Join Date: Sep 2012
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[QUOTE=sihaqqi;448455]

Hello Tobias and Marcos,

I have this same type of problem but like you I am not a very senior CFD specialist. I was trying to follow your comments but I do not understand how to resolve this issue. I have recently enrolled in postgrad by research student this is my first time with CFD and openfoam. I am solving for air flow in a pipe. Air is taken as compressible. So I am using rhoPimpleFoam. Can you please advise how I can get rid of this error.

I have applied following strategies

1. With small number of cells (coarse mesh), as rhoMax increases, number of time steps increase before solution fails.

2. As number of cells increase, as rhoMax increases, number of time steps decrease against the same number of rhoMax.

I have tried this strategy on cell size 13000, 26000 and 85000 for 8 trial cases for rhoMax 2, Pressure 100,000 and Temperature 300.

I have tried to increase pressure and temperatures also.

Upon increasing value of pressure to 200,000, error was produced at 0.0184 against 0.0181 at 100,000. The error came after only three more steps. Cell number is 13000. Value of rhoMax was kept as 2.

Upon increasing the value of temperature to 400, error was produced at 0.0458 against 0.0341 at 300. Cell number is 13000. Value of rhoMax was kept as 2.

I shall be very grateful.

Regards
Attached Images
 error.jpg (57.5 KB, 14 views)

August 28, 2013, 04:18
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Fellows

My image was very vague last time. I have reattached it so you may see the error.

Regards
Attached Images
 error.jpg (57.5 KB, 22 views)

 August 28, 2013, 11:57 #9 New Member   Vito Raso Join Date: Apr 2013 Location: Bari(Italy) Posts: 7 Rep Power: 5 Hi foamers, I'd like to understand how temperature is calculated in library hhuMixtureThermo.C because as you' ve explained in previous posts temperature is obtained from TH() function. However in hhuMixtureThermo library there are 3 functions to calculate unburnt(Tu) and burnt gas(Tb), mixture(T) temperature. It's clear how Tu and Tb are calculated: Code: ``` TuCells[celli] = this->cellReactants(celli).TH(huCells[celli], TuCells[celli]); TbCells[celli] = this->cellProducts(celli).TH(hCells[celli], TCells[celli]);``` Is mixture calculated from this function: Code: `TCells[celli] = mixture_.TH(hCells[celli], TCells[celli]);` or based upon Tu and Tb ? Thanks in advance, Vito

 March 15, 2016, 06:53 #10 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,555 Blog Entries: 6 Rep Power: 27 Hello guys, I do not know why this topic is not tracked anymore... so I am sorry for not replaying. I think your problems solved (2 years ago)... __________________ Best regards, Tobias Holzmann Some interesting OpenFOAM tutorials, publications and videos on www.Holzmann-cfd.de OpenFOAM Beginners should check out the new wiki on wiki.openfoam.com A list of some active OpenFOAM contributers can be found »here« A book about the basics of »Mathematics, Numerics, Derivations and OpenFOAM« can be found on www.Holzmann-cfd.de

 July 5, 2016, 15:17 Maximum number of iterations exceeded #11 New Member   Henry Join Date: May 2016 Posts: 15 Rep Power: 2 Hi Tobi, I've been having some problems with the "Maximum number of iterations exceeded" error. I've been pouring through the source code to find where the error is, but to I've got nowhere. Do you have any advice for how to go about solving this? The case is a wedge that I meshed using snappy Hex Mesh in the middle of a block mesh domain with an inlet, outlet, and symmetry plane on one side. This is what I got from the log file: Code: ```/*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 3.0.1 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 3.0.1-119cac7e8750 Exec : rhoCentralFoam -parallel Date : Jul 01 2016 Time : 12:54:38 Host : "bft-01-cfd01" PID : 30359 Case : /home/mpiuser/OpenFOAM/mpiuser-3.0.1/run/henry/wedge/wedge15maxIterError nProcs : 36 Slaves : 35 ( "bft-01-cfd01.30360" "bft-01-cfd01.30361" "bft-01-cfd01.30362" "bft-01-cfd01.30363" "bft-01-cfd01.30364" "bft-01-cfd01.30365" "bft-01-cfd01.30366" "bft-01-cfd01.30367" "bft-01-cfd01.30368" "bft-01-cfd01.30369" "bft-01-cfd01.30370" "bft-01-cfd02.26571" "bft-01-cfd02.26572" "bft-01-cfd02.26573" "bft-01-cfd02.26574" "bft-01-cfd02.26575" "bft-01-cfd02.26576" "bft-01-cfd02.26577" "bft-01-cfd02.26578" "bft-01-cfd02.26579" "bft-01-cfd02.26580" "bft-01-cfd02.26581" "bft-01-cfd02.26582" "bft-01-cfd03.29133" "bft-01-cfd03.29134" "bft-01-cfd03.29135" "bft-01-cfd03.29136" "bft-01-cfd03.29137" "bft-01-cfd03.29138" "bft-01-cfd03.29139" "bft-01-cfd03.29140" "bft-01-cfd03.29141" "bft-01-cfd03.29142" "bft-01-cfd03.29143" "bft-01-cfd03.29144" ) Pstream initialized with: floatTransfer : 0 nProcsSimpleSum : 0 commsType : nonBlocking polling iterations : 0 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 Reading thermophysical properties Selecting thermodynamics package { type hePsiThermo; mixture pureMixture; transport const; thermo hConst; equationOfState perfectGas; specie specie; energy sensibleInternalEnergy; } Reading field U Creating turbulence model Selecting turbulence model type laminar fluxScheme: Kurganov Starting time loop Mean and max Courant Numbers = 0.00521015 0.119072 deltaT = 2.4e-06 Time = 2.4e-06 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 diagonal: Solving for rhoUx, Initial residual = 0, Final residual = 0, No Iterations 0 diagonal: Solving for rhoUy, Initial residual = 0, Final residual = 0, No Iterations 0 diagonal: Solving for rhoUz, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for Ux, Initial residual = 0.999285, Final residual = 0.00389594, No Iterations 5 smoothSolver: Solving for Uy, Initial residual = 0.999999, Final residual = 8.69665e-17, No Iterations 5 smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 8.81879e-17, No Iterations 5 diagonal: Solving for rhoE, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for e, Initial residual = 1.46977e-11, Final residual = 1.46977e-11, No Iterations 0 ExecutionTime = 0.68 s ClockTime = 1 s Mean and max Courant Numbers = 0.00625242 0.142579 deltaT = 2.88e-06 Time = 5.28e-06 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 diagonal: Solving for rhoUx, Initial residual = 0, Final residual = 0, No Iterations 0 diagonal: Solving for rhoUy, Initial residual = 0, Final residual = 0, No Iterations 0 diagonal: Solving for rhoUz, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for Ux, Initial residual = 6.23273e-10, Final residual = 6.23273e-10, No Iterations 0 smoothSolver: Solving for Uy, Initial residual = 1.24042e-05, Final residual = 6.5351e-18, No Iterations 5 smoothSolver: Solving for Uz, Initial residual = 0.00028774, Final residual = 4.85118e-17, No Iterations 5 diagonal: Solving for rhoE, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for e, Initial residual = 5.7298e-12, Final residual = 5.7298e-12, No Iterations 0 [0] [1] [1] [1] --> FOAM FATAL ERROR: [1] Maximum number of iterations exceeded [1] [1] From function Foam::scalar Foam::species::thermo::T(Foam::scalar, Foam::scalar, Foam::scalar, Foam::scalar (Foam::species::thermo::*)(Foam::scalar, Foam::scalar)const, Foam::scalar (Foam::species::thermo::*)(Foam::scalar, Foam::scalar)const, Foam::scalar (Foam::species::thermo::*)(Foam::scalar)const) const [with Thermo = Foam::hConstThermo >; Type = Foam::sensibleInternalEnergy; Foam::scalar = double; Foam::species::thermo = Foam::species::thermo >, Foam::sensibleInternalEnergy>] [1] in file /home/openfoam/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 66. [1]``` My 0 files are here: p: Code: ```dimensions [1 -1 -2 0 0 0 0]; internalField uniform 18822.7; boundaryField { inlet { type fixedValue; value uniform 18822.7; } outlet { type zeroGradient; } airplane { type zeroGradient; } bottom { type zeroGradient; } top { type zeroGradient; } symmetry { type symmetryPlane; } left { type zeroGradient; } defaultFaces { type zeroGradient; } }``` T: Code: ```dimensions [0 0 0 1 0 0 0]; internalField uniform 216.65; boundaryField { inlet { type fixedValue; value uniform 216.65; } outlet { type zeroGradient; } airplane { type zeroGradient; } bottom { type zeroGradient; } top { type zeroGradient; } left { type zeroGradient; } symmetry { type symmetryPlane; } defaultFaces { type zeroGradient; } }``` U: Code: ```dimensions [0 1 -1 0 0 0 0]; internalField uniform (400 0 0); //(246.933 0 0); boundaryField { inlet { type fixedValue; value uniform (400 0 0); } outlet { type zeroGradient; } airplane { type slip; } bottom { type zeroGradient; } top { type zeroGradient; } left { type zeroGradient; } symmetry { type symmetryPlane; } defaultFaces { type zeroGradient; } }```

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