[AMR96]

Hello,

I have to simulate external aerodynamics around a vehicle while turning using OpenFoam. Since I have never used OpenFoam before, I am trying to start from something more simple. I have been trying to simulate the flow around an Ahemdbody on a straight line. The dimensions of the domain are 15m x 1.87m x 1.4m and the Ahemdbody is placed in the middle of the channel. I have cut the domain in half in order to save computational power and time.

I already managed to do this simulation on Ansys and got good results for the lift and drag coefficients but I just can't get the same results on OpenFoam. I am using the same mesh that I used in Ansys by importing it into OF using the fluent3DMeshToFoam feature.

I am running the simulation using simpleFoam with realizable k-epsilon model. The residuals seem to decrease to the order of 1e-4 however the lift and drag coefficients keep oscillating in the range of 0.3-0.4 and never approach the experimental values. I ran the simulation for 1000 iterations.

Below I have provided the boundary conditions that I used, also attached you can find the fvscheme, fvsolution, and the last 50 iterations of the simulation.

I would appreciate any help that would guide me in the right direction and help me find where the problem is.

Here is the checkMesh results which seems to be ok.

Mesh stats
    points:           605703
    internal points:  564818
    faces:            6232198
    internal faces:   6154064
    cells:            3040478
    faces per cell:   4.0737877
    boundary patches: 5
    point zones:      0
    face zones:       1
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     0
    prisms:        224350
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    2816128
    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               130      100      ok (non-closed singly connected)
    outlet              132      101      ok (non-closed singly connected)
    ground              22220    11398    ok (non-closed singly connected)
    car                 22650    11491    ok (non-closed singly connected)
    symmetry            33002    18681    ok (non-closed singly connected)

Checking faceZone topology for multiply connected surfaces...
    FaceZone            Faces    Points   Surface topology
    interior-geom-enclosure_enclosure6154064  605703   multiply connected (shared edge)
  <<Writing 605001 conflicting points to set nonManifoldPoints

Checking basic cellZone addressing...
    CellZone            Cells        Points       Volume       BoundingBox
    geom-enclosure_enclosure 3040478      605703       19.579551    (-1.1268994 -0.7405 -7.448) (0.27310058 0.1945 7.552)

Checking geometry...
    Overall domain bounding box (-1.1268994 -0.7405 -7.448) (0.27310058 0.1945 7.552)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (1.7931218e-15 -7.4856584e-16 4.2947788e-18) OK.
    Max cell openness = 3.0197195e-16 OK.
    Max aspect ratio = 8.2230522 OK.
    Minimum face area = 4.082886e-07. Maximum face area = 0.020149883.  Face area magnitudes OK.
    Min volume = 1.09952e-10. Max volume = 0.0012024398.  Total volume = 19.579551.  Cell volumes OK.
    Mesh non-orthogonality Max: 66.847134 average: 15.459832
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 2.3554795 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

Here are the boundary conditions:
U

internalField   uniform (0.0 0.0 -40.0);

boundaryField
{

    inlet
        {
            type            fixedValue;
            value           uniform ( 0.0 0.0 -40.0 );
        }

    ground
    {
        
        type        fixedValue;
        value       uniform (0 0 0);
    }

    outlet
    {
        type            inletOutlet;
        value           uniform (0 0 0);
        inletValue      uniform (0 0 0);
    }

    car
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }

    symmetry
    {
        type        symmetry;
        
    }

}

pressure

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0.0;

boundaryField
{

    inlet
    {
        type        zeroGradient;
    }

    ground
    {
        type        zeroGradient;
    }

    outlet
    {
        type            fixedValue;
        value           uniform 0;
    }

    car
    {
        type        zeroGradient;
    }

    symmetry
    {
        type        symmetry;
        
    }

}

epsilon

dimensions      [0 2 -3 0 0 0 0];

internalField   uniform 34.56;

boundaryField
{

    inlet
    {
         type            fixedValue;
         value           $internalField;
    }

    ground
    {
        type        epsilonWallFunction;
        value       $internalField;
    }

    outlet
    {
        type        inletOutlet;
        inletValue  $internalField;
        value       $internalField;
    }

    car
    {
        type        epsilonWallFunction;
        value       $internalField;
    }

    symmetry
    {
        type        symmetry;
        
    }

}

k

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0.24;

boundaryField
{

    inlet
    {
        type            fixedValue;
        value           $internalField;
    }

    ground
    {
        type        kqRWallFunction;
        value       $internalField;
    }

    outlet
    {
        type            inletOutlet;
        inletValue      $internalField;
        value           $internalField;
    }

    car
    {
        type        kqRWallFunction;
        value       $internalField;
    }

    symmetry
    {
        type        symmetry;
    }

}

[AMR96]

Can anybody help please )