SimScale CAE Forum

Difficulty in Meshing and Boundary generation


#1

Hi all,
I have been trying to mesh the diffuser geometry for quite some time now with no success.
I am new to SimScale ( OpenFoam ) and SnappyHex meshing. No boundary layers are generated on diffuser geometry.

The following is the recurrent theme in the meshing log which I think is the problem.
–> FOAM Warning :
From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList&, bool, bool) const
in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 782
Cannot find any patch or group names matching solid_0_undertray_part_design
–> FOAM Warning :
From function Foam::layerParameters::layerParameters(const Foam::dictionary&, const Foam::polyBoundaryMesh&)
in file snappyHexMeshDriver/layerParameters/layerParameters.C at line 274
Reading “system/snappyHexMeshDict.addLayersControls.layers” from line 68 to line 71
Layer specification for solid_0_undertray_part_design does not match any patch.
Valid patches are
17
(
boundingBox1
boundingBox2
boundingBox3
boundingBox4
boundingBox5
boundingBox6
solid_0
procBoundary0to1
procBoundary0to2
procBoundary0to3
procBoundary0to4
procBoundary0to5
procBoundary0to6
procBoundary0to7
procBoundary0to13
procBoundary0to14
procBoundary0to15
)

The following is the link to my project: https://www.simscale.com/workbench?publiclink=976556b0-5a89-498d-99f3-d2dbcfc68f07

Any additional tips and suggestions will be helpful!


#2

Hi @amaknojia, what is this for? are you trying to simulate fluid running through the channels from one side to the other?

I noticed the bounding box wasn’t touching the model, this is how I would imagine it being set up. Once I know what you are trying to achieve i’ll have a go meshing it for you.

Cheers,
Darren


#3

Hi Darren,
Sorry for the incomplete case set up. I tried many times but it failed.

The simulation is basically external aerodynamics for the diffuser ( undertray ).

It works in close proximity with the ground to develop low pressure underneath race car and generates downforce.

I approached the problem by employing symmetry. The bounding box details are

The body along with the floor (Zmin ) is to be inflated. The geometry is at designed ground clearance of 63 mm (Zmin=0)

I hope this helps with the simulation setup.
Regards,
Aziz


#4

Hi @amaknojia, here is a link:
https://www.simscale.com/workbench?publiclink=a0863077-6912-428d-a560-1e749b05ec5a

I have a mesh there and it does inflate the layers:

I think a few of the refinements were over refined so could do with reducing, also I think to get the floor layers at uniform thickness we should explicitly define them instead of relatively defining them (this is done in the main mesh settings). I added a region to try capture some of the physics when leaving the diffuser.

This is a good starting point but I would spend some time refining it :slight_smile:

If I can help with anything else just tag me,
Darren