[morkman]

I have created a vehicle and output a STL file. First I want to use snappyHexMesh to convert the STL file to the proper format for OpenFOAM. Then I want to run a few airflow simulations

I am using OpenFOAM's 5.x and my case directory is here: https://github.com/anujgoyal/openfoam

Slide 13 of this presentation: http://openfoamwiki.net/images/f/f0/...SlidesOFW7.pdf says that 5 requirements are needed:

• Geometry data (stl, nas, obj) in constant/triSurface/Simple Car CFD.STL [DONE]
• Dictionary file system/snappyHexMeshDict [DONE, don't know if it is correct]
• Hexahedral base mesh (decomposed if running in parallel) [?, don't know where to start]
• Dictionary file system/decomposeParDict for parallel runs [?, I have a large Xeon system so I would like to use parallel runs]
• All system dictionaries (e.g controlDict, fvSchemes, fvSolutions) [?, don't know what the minimal set of parameters are]

I am having some trouble understanding what values should be in the Hexahedral base mesh, controlDict, fvSchemes and fvSolutions - does anyone have any recommendations? or could you point me to some detailed tutorials that they recommend?



I have also cross-referenced it on stackoverflow.com
https://stackoverflow.com/questions/...le-in-openfoam

[rajan19us]

You can use Helyx-OS (on Linux) to mesh, setup the case and run it.
The base mesh sizing depends upon the size of your model.
Tutorials you can find in the OpenFoam/tutorials directory.
I hope it helps a bit.

[Alasir]

Hex base mesh:
Snappyhexmesh basically works by using a large cubic mesh (base mesh) that surrounds your car, and removes all cells that are inside your car, and then gives you the remaining mesh. Exactly HOW you create this base mesh is irrelevant, but blockMesh is usually a good option.

snappyHexMeshDict:
This describes how exact the car is removed. If the end result is not awesome, then modify this until it is. You will most certainly have to do this quite a few times.

For parallell runs of multiple processors:
You will basically have to divide the mesh into multiple equal parts, and then each processor takes one part. Then reconstruct the mesh once the simulation is done. The decomposeParDict defines how the mesh should be split.

fvSolutions:
This defines how accurate the calculation needs to be. If you have converge problems, look here. If you have to strict requirements, your calculation gets much slower than it needs to be.

fvSchemes:
This defines what mathematical functions Openfoam should use to calculate your solution.

controlDict:
This is the main control document for the simulation. Note especially the timesteps and write interval.


I suggest going to the tutorial cases, and trying to find a case simular to your own, then adapt it to fit your needs. I imagine examining <incompressible/pisofoam/les/motorbike> would be interesting to you.

[Alasir]

I belive there also is a good youtube tutorial available.

[hulli]

https://openfoamwiki.net/images/f/f0...SlidesOFW7.pdf

[emregungor]

Originally Posted by morkman

I have created a vehicle and output a STL file. First I want to use snappyHexMesh to convert the STL file to the proper format for OpenFOAM. Then I want to run a few airflow simulations

I am using OpenFOAM's 5.x and my case directory is here: https://github.com/anujgoyal/openfoam

Slide 13 of this presentation: http://openfoamwiki.net/images/f/f0/...SlidesOFW7.pdf says that 5 requirements are needed:

• Geometry data (stl, nas, obj) in constant/triSurface/Simple Car CFD.STL [DONE]
• Dictionary file system/snappyHexMeshDict [DONE, don't know if it is correct]
• Hexahedral base mesh (decomposed if running in parallel) [?, don't know where to start]
• Dictionary file system/decomposeParDict for parallel runs [?, I have a large Xeon system so I would like to use parallel runs]
• All system dictionaries (e.g controlDict, fvSchemes, fvSolutions) [?, don't know what the minimal set of parameters are]

I am having some trouble understanding what values should be in the Hexahedral base mesh, controlDict, fvSchemes and fvSolutions - does anyone have any recommendations? or could you point me to some detailed tutorials that they recommend?



I have also cross-referenced it on stackoverflow.com
https://stackoverflow.com/questions/...le-in-openfoam

Hello morkman,

I have been trying similar study like your case. Did you manage this problem? If you did this case, would you describe for me (step by step) that how can I modify/replace my Car.stl file instead of the motorBike case? Thanks,