How can I mesh for CFD of turbulent jet

Coreform Cubit Meshing
#1

Hello Cubit users,

I am new, just created an account. I am also new to Cubit, so please keep it simple.

I have a specific problem for a relatively simple configuration. I want to simulate a turbulent jet (round or plane) – that is a flow entering via a small inlet pipe (diameter D) into a large domain (typical diameter 50D, length 100D – this domain could be conical or a box, so long as the side wall are far from the jet centerline) of the same fluid and density. I am currently using the nek5000 example NekExamples/turbJet/turbJet at master · Nek5000/NekExamples · GitHub. In README.md they say “The mesh was generated in Cubit, exported as EXODUSI and storred at ./turbJet/mesh/jet.exo. Finally it was converted to nek format using ext2nek”.

I want to adapt this code, and I would like to generate new meshes via Cubit like they do above. The meshes would look like this one: Unstructured spectral element mesh for large-eddy simulation of a turbulent jet. – Theoretical Fluid Dynamics and Turbulence Group

However, I am unfamiliar with Cubit at the current time, and I would like to ask:
(1) Are there Cubit tutorials for such basic CFD/jet mesh setups – if so, can you direct me a few links?
(2) Are there already example templates/tutorials that I could use?

Is there anyone kind enough to guide me through the initial phases?

Thanks.
Best wishes
Nadeem

#2

Hello @nadeem,
a mesh like the example from above can be easily done with a few lines.

grafik
grafik930×566 16.8 KB 

reset
create Cylinder height 20 radius 5 
create Cylinder height 1 radius 0.5
move volume 1 z 10
move volume 2 z -0.5
create surface circle radius 1.5 zplane
create surface circle radius 3.75 zplane
create surface circle radius 2.75 zplane
move Surface 8 9 z 20 include_merged preview 
move Surface 8 9 z 20 include_merged 
create volume loft surface 7 8  
create volume loft surface 6 9 
delete surface all
subtract volume 7 from volume 1 6 keep_tool
subtract volume 6  from volume 1  keep_tool
imprint vol all
merge vol all
surface 23 scheme hole rad_intervals 3 
vol 1 size 1
vol 2 size 0.05
mesh vol all

I am not aware of a tutorial colletion for CFD/jet mesh setups but we’ve got a lot of training material on our website.

If you are totally new to cubit i would recommend doing the training classes. They will help greatly to get accustomed to the cubit workflow.

When you need any help in the future just reach out in the forum.