[sandrobrad]

Hi there!,
I'm just wondering if I'm able to know what are the values of k and omega using SpalartAllmaras model.

My idea is to implement the follwing code in the controlDict:

turbulenceFields1
    {
        // Mandatory entries (unmodifiable)
        type            turbulenceFields;
        libs            (fieldFunctionObjects);

        // Mandatory entries (runtime modifiable)
        // Either field or fields entries
        
        field k;
        field omega;

        // Optional (inherited) entries
    
        enabled         true;
        log             true;
        timeStart       0;
        timeEnd         20000;
        executeControl  timeStep;
        executeInterval 1;
        writeControl    timeStep;
        writeInterval   1;
    }

Eventually, I wasn't able to get these values because the following error appears:

#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2  ? in /lib/x86_64-linux-gnu/libpthread.so.0
#3  Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4  void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) at ??:?
#5  Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::operator/<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&) at ??:?
#6  Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::functionObjects::turbulenceFields::omega<Foam::IncompressibleTurbulenceModel<Foam::transportModel> >(Foam::IncompressibleTurbulenceModel<Foam::transportModel> const&) const at ??:?
#7  Foam::functionObjects::turbulenceFields::execute() at ??:?
#8  Foam::functionObjects::timeControl::execute() at ??:?
#9  Foam::functionObjectList::execute() at ??:?
#10  Foam::Time::run() const at ??:?
#11  Foam::Time::loop() at ??:?
#12  Foam::simpleControl::loop() at ??:?
#13  ? in /usr/lib/openfoam/openfoam2106/platforms/linux64GccDPInt32Opt/bin/simpleFoam
#14  __libc_start_main in /lib/x86_64-linux-gnu/libc.so.6
#15  ? in /usr/lib/openfoam/openfoam2106/platforms/linux64GccDPInt32Opt/bin/simpleFoam
Floating point exception (core dumped)

Do you have any idea about what's going on or where shoould I start? Is it posible to get k omega values if I'm using other turbulence model?
Thanks in advance.

[Yann]

Hi Sandro,

All the RANS turbulence models in OpenFOAM computes the turbulence visocity nut. Each model uses a specific set of equations for this.

Spalart-Almaras is a one equation model computing a modified turbulence viscosity named nuTilda.
The k-omega family is based on a two equation model computing the kinetic energy (k) and turbulence specific dissipation rate (omega).

Spalart-Almaras does not have anything to do with k and omega so you cannot get these values from a case running with Spalart-Almaras. Generally speaking, when you are using a turbulence model you can only access to variables computed by this model.

Yann

[HPE]

With v2106, you should be able to estimate (see Yann's comments) k and omega field from the SpalartAllmaras model: openfoam-v2106/solver-and-physics#turbulence-field-estimation

With which version have you tried your case? If that was the v2106, could you post a MWE, so that we can reproduce the error?

Thanks.

[HPE]

Also the correct syntax is:

fields( k omega );

[Yann]

Good point HPE, I did not know this function object.

My bad, I should have had a look at it after reading Sandro's initial post.

Thanks,
Yann

[sandrobrad]

Okay I implemented the following function in the controlDict:

turbulenceFields1
    {
        // Mandatory entries (unmodifiable)
        type            turbulenceFields;
        libs            (fieldFunctionObjects);

        // Mandatory entries (runtime modifiable)
        // Either field or fields entries
        
        fields
            (
            k
            epsilon
            nut
            nuEff
            R
            devReff
            L
            I
            );

        // Optional (inherited) entries
    
        enabled         true;
        log             true;
        timeStart       0;
        timeEnd         20000;
        executeControl  timeStep;
        executeInterval 100;
        writeControl    timeStep;
        writeInterval   100;
    }

Then I start the simulation and every 100 step the solver creates a folder corresponding to the timesimulation, every 100s and so on. Well, my question is that I don't know what's the file created called turbulenceProperties:k,turbulencePropertiesmega. ... . I mean, I don't know how to interpret that amount of values. Please could you help me telling me what is the purpose of these values because I'm looking for initial values of omega, k in order to start to use the komegasst turbulence model.

By other hand, since the beginning I wanted to sim using the komegaSST but I don't know the initial omega and k values. So I thought that using the spalartallmaras turbulence model, checking the values of k and omega and use these values could be a good idea but, ¿what values from the spalartallmaras sim should I use in order to get these values? Thanks in advance and feel free to ask me whatever you want.
Best regards and thanks for ur answers.

[sandrobrad]

Note that in the fields I didn't add the omega. When I add that feature the simulation stops and the following message prints out :

 PyFoam WARNING on line 37 of file /home/sandrobrad/.local/lib/python3.8/site-packages/PyFoam/Infrastructure/ServerBase.py : No certficate file /home/sandrobrad/.pyFoam/foamServerCertificate.cert exists. Therefor no SSL-connection for the FoamServer possible
 To generate a private key:
    openssl genrsa -out /home/sandrobrad/.pyFoam/foamServerCertificate.key 2048 
Then generate the cerificate that is valid for 3 years with 
    openssl req -new -x509 -key /home/sandrobrad/.pyFoam/foamServerCertificate.key -out /home/sandrobrad/.pyFoam/foamServerCertificate.cert -days 1095 
/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2106                                  |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : _7b82832f-20210625 OPENFOAM=2106
Arch   : "LSB;label=32;scalar=64"
Exec   : simpleFoam
Date   : Oct 08 2021
Time   : 23:54:39
Host   : sandrobrad-GL753VD
PID    : 11703
I/O    : uncollated
Case   : /home/sandrobrad/steady0012/spalartallmaras
nProcs : 1
trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 5, maxFileModificationPolls 20)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0


SIMPLE: convergence criteria
    field p     tolerance 1e-10
    field U     tolerance 1e-10
    field nuTilda     tolerance 1e-10
    field "(k|epsilon|omega)"     tolerance 1e-10

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type RAS
Selecting RAS turbulence model SpalartAllmaras
Selecting patchDistMethod meshWave
RAS
{
    RASModel        SpalartAllmaras;
    turbulence      on;
    printCoeffs     on;
    sigmaNut        0.666667;
    kappa           0.41;
    Cb1             0.1355;
    Cb2             0.622;
    Cw2             0.3;
    Cw3             2;
    Cv1             7.1;
    Cs              0.3;
}

No MRF models present

No finite volume options present

Starting time loop

turbulenceFields turbulenceFields1: storing fields:
    turbulenceProperties:nut
    turbulenceProperties:nuEff
    turbulenceProperties:k
    turbulenceProperties:R
    turbulenceProperties:I
    turbulenceProperties:L
    turbulenceProperties:devReff
    turbulenceProperties:omega
    turbulenceProperties:epsilon

forceCoeffs forceCoeffs1:
    rho: rhoInf
    Freestream density (rhoInf) set to 1.225
    Not including porosity effects

Time = 1

smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = 0.00635739, No Iterations 12
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = 0.00335301, No Iterations 12
GAMG:  Solving for p, Initial residual = 1, Final residual = 0.00993536, No Iterations 181
time step continuity errors : sum local = 0.000983448, global = 2.92864e-06, cumulative = 2.92864e-06
smoothSolver:  Solving for nuTilda, Initial residual = 1, Final residual = 0.00868777, No Iterations 12
ExecutionTime = 1.69 s  ClockTime = 1 s

#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2  ? in /lib/x86_64-linux-gnu/libpthread.so.0
#3  Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4  void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) at ??:?
#5  Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::operator/<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&) at ??:?
#6  Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::functionObjects::turbulenceFields::omega<Foam::IncompressibleTurbulenceModel<Foam::transportModel> >(Foam::IncompressibleTurbulenceModel<Foam::transportModel> const&) const at ??:?
#7  Foam::functionObjects::turbulenceFields::execute() at ??:?
#8  Foam::functionObjects::timeControl::execute() at ??:?
#9  Foam::functionObjectList::execute() at ??:?
#10  Foam::Time::run() const at ??:?
#11  Foam::Time::loop() at ??:?
#12  Foam::simpleControl::loop() at ??:?
#13  ? in /usr/lib/openfoam/openfoam2106/platforms/linux64GccDPInt32Opt/bin/simpleFoam
#14  __libc_start_main in /lib/x86_64-linux-gnu/libc.so.6
#15  ? in /usr/lib/openfoam/openfoam2106/platforms/linux64GccDPInt32Opt/bin/simpleFoam
Floating point exception (core dumped)

And you may wondering, how do you know that issue is related with the omega?.
Okay, I know it beacause if I eliminate the omega in the fields, the sim works perfectly. So , there is something strange with the omega in that function. Do you know what is going on? Thanks in advance.