Contra-rotating propeller simulation

Question

I obtained a hexpress surface to volume mesh of the countra-rotating propeller (I followed the meshing tutoral "Meshing the PPTC Propeller using surface-to-volume meshing"). Should I add a rotating sub-domain or is it possible to make the individual props rotate withou it?

Benoit Mallol · Accepted Answer

Hi, 
 my advice would be to create 3 separate meshes: 1 for the external part and 1 per propeller unit. Making the propeller unit with S2V (surface to volume) is totally fine and you can make the external one with V2S (Volume to surface). This means the external one should have 2 cylindrical holes so that you can combine all meshes together later on. See picture attached. 
 To combine all meshes in Fine Marine: 
 
 Export each mesh from Fidelity to Hexpress format (.hex) 
 Open Hexpress and import and meshes one by one and save them under a new project (Hexpress will then consider this mesh as a multi domain project). 
 Open Fine Marine and take this new combined mesh to setup the simulation. 
 You can then freely define the rotating speed for each propeller unit and impose a velocity at the inlet of your external domain. 
 The main difficulty in Fine Marine would be the time step: it should be small enough to comply with the rule of dividing 1 rotation in 200 time steps for instance.

Best regards, 
 Benoit

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Contra-rotating propeller simulation

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