[xsa]

Hi Foamers,
I am trying to simulate the heating that occurs in an induction motor, alongside with the cooling of it with the help of an external fan. The induction motor looks like in the attached image (cut in half).

The domain with the red color is the air and the rest are the different components of the motor like the stator and rotor.
I exported the mesh with ideasUnvToFoam with the file exported from Salome, consisting of tetrahedra cells. The checkMesh log file looks like this.

Mesh stats
    points:           312343
    faces:            3585501
    internal faces:   3550655
    cells:            1784039
    faces per cell:   4
    boundary patches: 3
    point zones:      0
    face zones:       0
    cell zones:       6

Overall number of cells of each type:
    hexahedra:     0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    1784039
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    inlet               164      100      ok (non-closed singly connected)  
    outlet              2629     1444     ok (non-closed singly connected)  
    defaultFaces        32053    16174    ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (-0.2277233 -0.22612136 -0.35775) (0.2292767 0.23087864 0.38025)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (3.0428315e-017 3.5912087e-018 4.5874614e-017) OK.
    Max cell openness = 3.1519565e-016 OK.
    Max aspect ratio = 9.1970767 OK.
    Minimum face area = 1.1271098e-007. Maximum face area = 0.000228302.  Face area magnitudes OK.
    Min volume = 1.8090004e-011. Max volume = 1.0056312e-006.  Total volume = 0.091300385.  Cell volumes OK.
    Mesh non-orthogonality Max: 68.406458 average: 17.469148
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.7404942 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

The simulation consists of some heat sources in the rotor and stator and an airflow inlet of 0,2 m3/s. I am running with the solver chtMultiRegionSimpleFoam and the simulation starts but I get time step continuity errors and when it reaches the 7th second, the iterations of solving p_rgh suddenly increase to the limit. The error log file looks like this:

Time = 5


Solving for fluid region air
smoothSolver:  Solving for Ux, Initial residual = 0.21578625, Final residual = 0.010209813, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.26924827, Final residual = 0.01026977, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 0.14502202, Final residual = 0.0060408645, No Iterations 3
GAMG:  Solving for h, Initial residual = 0.31451636, Final residual = 0.00035917851, No Iterations 1
Min/max T:299.97213 300.16361
GAMG:  Solving for p_rgh, Initial residual = 0.020587446, Final residual = 0.00012616458, No Iterations 5
GAMG:  Solving for p_rgh, Initial residual = 0.011918253, Final residual = 6.4418955e-005, No Iterations 2
time step continuity errors : sum local = 13.092179, global = 3.034886, cumulative = 4.7881806
Min/max rho:1.15857 42.31626
smoothSolver:  Solving for epsilon, Initial residual = 0.45136702, Final residual = 0.01080506, No Iterations 4
smoothSolver:  Solving for k, Initial residual = 0.28291767, Final residual = 0.0067125576, No Iterations 4

Solving for solid region carcasa
smoothSolver:  Solving for h, Initial residual = 0.062395741, Final residual = 6.6960944e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.036724725, Final residual = 6.0332786e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.027209336, Final residual = 5.284252e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.021678707, Final residual = 4.7436983e-007, No Iterations 11
Min/max T:299.99999 300.04461

Solving for solid region estator
smoothSolver:  Solving for h, Initial residual = 0.055643605, Final residual = 6.6323807e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.051877492, Final residual = 6.0780338e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.043999489, Final residual = 5.6605775e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.040695944, Final residual = 5.3075743e-007, No Iterations 12
Min/max T:300.00334 300.10069

Solving for solid region paquete
smoothSolver:  Solving for h, Initial residual = 0.058619361, Final residual = 6.8645591e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.052623025, Final residual = 6.431375e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.047983007, Final residual = 6.0354914e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.044679787, Final residual = 5.6956311e-007, No Iterations 12
Min/max T:300.00166 300.20722

Solving for solid region rotor
smoothSolver:  Solving for h, Initial residual = 0.24895255, Final residual = 5.4206869e-007, No Iterations 14
smoothSolver:  Solving for h, Initial residual = 0.23538873, Final residual = 5.1776333e-007, No Iterations 14
smoothSolver:  Solving for h, Initial residual = 0.22339747, Final residual = 4.9532464e-007, No Iterations 14
smoothSolver:  Solving for h, Initial residual = 0.21173401, Final residual = 4.7114533e-007, No Iterations 14
Min/max T:300.02767 300.12027

Solving for solid region eje
smoothSolver:  Solving for h, Initial residual = 0.053108372, Final residual = 7.7474521e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.041939269, Final residual = 6.7947562e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.034449824, Final residual = 5.984097e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.029809757, Final residual = 5.4919018e-007, No Iterations 11
Min/max T:300 300.0472
ExecutionTime = 1551.259 s  ClockTime = 1551 s

Time = 6


Solving for fluid region air
smoothSolver:  Solving for Ux, Initial residual = 0.14536389, Final residual = 0.0028420734, No Iterations 3
smoothSolver:  Solving for Uy, Initial residual = 0.1776137, Final residual = 0.0082670569, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 0.077735287, Final residual = 0.0021526489, No Iterations 3
GAMG:  Solving for h, Initial residual = 0.27370362, Final residual = 0.00032454368, No Iterations 1
Min/max T:299.91886 300.20152
GAMG:  Solving for p_rgh, Initial residual = 0.11728298, Final residual = 0.00097518063, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 0.011725349, Final residual = 9.0269481e-005, No Iterations 2
time step continuity errors : sum local = 48.434583, global = -0.69965801, cumulative = 4.0885226
Min/max rho:1.1584873 77.331698
smoothSolver:  Solving for epsilon, Initial residual = 0.34649269, Final residual = 0.00827647, No Iterations 4
smoothSolver:  Solving for k, Initial residual = 0.21215974, Final residual = 0.0048938131, No Iterations 4

Solving for solid region carcasa
smoothSolver:  Solving for h, Initial residual = 0.047114892, Final residual = 5.5770834e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.029313556, Final residual = 5.1500126e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.022470358, Final residual = 4.6051181e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.018371939, Final residual = 4.1948118e-007, No Iterations 11
Min/max T:299.99998 300.05785

Solving for solid region estator
smoothSolver:  Solving for h, Initial residual = 0.046429597, Final residual = 5.400198e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.044012641, Final residual = 5.0060242e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.036691329, Final residual = 4.712569e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.034245203, Final residual = 4.4579687e-007, No Iterations 12
Min/max T:300.00437 300.12382

Solving for solid region paquete
smoothSolver:  Solving for h, Initial residual = 0.048195464, Final residual = 5.6117088e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.043632525, Final residual = 5.3137647e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.040063593, Final residual = 5.0325471e-007, No Iterations 12
smoothSolver:  Solving for h, Initial residual = 0.037600986, Final residual = 4.7882229e-007, No Iterations 12
Min/max T:300.00231 300.24237

Solving for solid region rotor
smoothSolver:  Solving for h, Initial residual = 0.20894768, Final residual = 4.5419299e-007, No Iterations 14
smoothSolver:  Solving for h, Initial residual = 0.19869693, Final residual = 4.3668252e-007, No Iterations 14
smoothSolver:  Solving for h, Initial residual = 0.18949435, Final residual = 4.2009112e-007, No Iterations 14
smoothSolver:  Solving for h, Initial residual = 0.18073094, Final residual = 4.021397e-007, No Iterations 14
Min/max T:300.03535 300.14188

Solving for solid region eje
smoothSolver:  Solving for h, Initial residual = 0.043873939, Final residual = 6.6680866e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.03563445, Final residual = 5.9662922e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.029814852, Final residual = 5.3286034e-007, No Iterations 11
smoothSolver:  Solving for h, Initial residual = 0.026125858, Final residual = 4.9347162e-007, No Iterations 11
Min/max T:300 300.05855
ExecutionTime = 1813.066 s  ClockTime = 1813 s

Time = 7


Solving for fluid region air
smoothSolver:  Solving for Ux, Initial residual = 0.17284958, Final residual = 0.007962946, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.19257908, Final residual = 0.0080746212, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 0.15193187, Final residual = 0.0068897998, No Iterations 3
GAMG:  Solving for h, Initial residual = 0.15194215, Final residual = 0.00015001932, No Iterations 1
Min/max T:299.93498 300.23818
GAMG:  Solving for p_rgh, Initial residual = 0.011104256, Final residual = nan, No Iterations 1000
GAMG:  Solving for p_rgh, Initial residual = nan, Final residual = nan, No Iterations 1000


--> FOAM FATAL IO ERROR: 
wrong token type - expected Scalar, found on line 0 the word 'nan'

file: C:/.../system/air/data.solverPerformance.p_rgh at line 0.

    From function operator>>(Istream&, Scalar&)
    in file lnInclude/Scalar.C at line 93.

FOAM exiting

I have read that the issue could be with fvSolution, fvSchemes or with the BC, and I had some problems before with them and I managed to handle them but I got stuck with this issue right now. My fvSolution and fvSchemes are this:

solvers
{
    rho
    {
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-05;
        relTol          0.01;
    }
    p_rgh
    {
        solver        GAMG;
    smoother    DICGaussSeidel;
        tolerance    1e-08;
        relTol        0.01

    }
    "(U|k|epsilon|R)"
    {
        solver        smoothSolver;
    smoother    symGaussSeidel;
        tolerance    1e-05;
        relTol        0.05;
    }
    h
    {
        solver        GAMG;
    smoother    DILUGaussSeidel;
        tolerance    1e-07;
        relTol        0.01;
    }

}

SIMPLE
{
    nNonOrthogonalCorrectors 1;

    residualControl
    {
        p_rgh    1e-6;
        U    1e-4;
    }
    
    pRefCell    0;
    pRefValue    0.0;
}

relaxationFactors
{
    fields
    {
        rho    1;
        p_rgh    0.3;
    }

    equations
    {
            "h.*"           0.7;
            "U.*"           0.7;
        k        0.7;
        epsilon        0.7;
    }
}

// ************************************************************************* //

ddtSchemes
{
    default steadyState;
}

gradSchemes
{
    default        cellMDLimited Gauss linear 0.5;
    grad(U)        cellMDLimited Gauss linear 0.5;
}

divSchemes
{
    default         none;

    div(phi,U)      bounded Gauss linearUpwind grad(U);
    div(phi,K)      bounded Gauss linear;
    div(phi,h)      bounded Gauss linearUpwind default ;
    div(phi,k)      bounded Gauss linearUpwind default;
    div(phi,epsilon) bounded Gauss linearUpwind default;
    div(phi,R)      Gauss linearUpwind default;
    div(R)          Gauss linear;
    div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;

}

laplacianSchemes
{
    default        Gauss cubic limited 0.5;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         limited 0.5;
}

// ************************************************************************* //

and the BC’s of the air are attached in the .zip file.


Does someone have an idea of how to solve the problem?
How to decrease the time step continuity errors and the divergence of p_rgh?


Thanks in advance