[Maveryck]

Hi everyone

currently I'm working on turbulence simulation with k-epsilon model over a cylinder channel. I'm getting a wird plot for all the variables and I'm pretty sure is because of the mesh, as you can see on the attached images the wird values of variable k are exactly located over the edges of the central block so I suspect there has to be a better way to mesh.

Any suggestion will be welcome



k.png
Mesh.jpg

[virengos]

Hi Maveryck,
can you provide some more details?
- boundary conditions, model definition?
- geometry size, dimensions and scaling ok ?
best,
Damian

[Carlo_P]

Hey Maverick,
take a look here:
https://sites.google.com/site/snappy.../cylinder-case

[Maveryck]

Originally Posted by virengos

Hi Maveryck,
can you provide some more details?
- boundary conditions, model definition?
- geometry size, dimensions and scaling ok ?
best,
Damian

It is a quite simple case, cyclic on the inlet and outlet with the following boundary conditions (it is worth mentioning that yPlus at the walls is 0.2 approximately):

Epsilon boundary conditions

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

internalField   uniform 0.6;

boundaryField
{
    inlet 
    { 
        type            cyclic;
    } 

    outlet
    {
        type            cyclic;
    }

    FixedWalls
    {
     type     zeroGradient;
          
    }
}

k boundary conditions

internalField   uniform 0.05;

boundaryField
{
    inlet 
    { 
        type            cyclic;
    } 

    outlet
    {
        type            cyclic;
    }

    FixedWalls
    {
     type     fixedValue;
     value     uniform 1.0e-08;
    }
}

U boundary conditions

internalField   uniform (0.1 0 0);

boundaryField
{
     inlet 
     { 
        type            cyclic;
     } 

    outlet
    {
        type            cyclic;
    }

    FixedWalls
    {
        type            noSlip;
    }
}

The domain is a pipe with diameter = 0.1m and length = 0.1m and bulk velocity is fixed to 1.9 m/s through a momentumSource:

momentumSource
{
    type            meanVelocityForce;
    active          yes;

    selectionMode   all;

    fields          (U);
    Ubar            (1.9 0 0);
}