Transforming mesh 360 degree in CFX Pre

AS_Aero · July 20, 2018, 08:28

Hi

I am trying to mesh a rotor body which is having 20 blades and its a huge geometry. So I was thinking if its a good idea to cut only a small wedge from the geometry and then transform the mesh in CFX Pre using rotation option. But some people told me its not a good way to do and it might create problem for the simulation. Can someone tell me if its a right way to do and will there is be any issue by doing so ?

Opaque · July 20, 2018, 09:55

The standard practice in turbomachinery is to mesh a single passage/sector of the geometry whenever there is true geometric periodicity

Then replicate the "base sector" to as many copies needed for the model. Some models may only need one sector, some two sectors (Fourier Transformation for example), or more sectors (full 360).

The best practice when replicating rotationally periodic sectors is to use the "Turbo Rotation" option in the Mesh Transformation. You indicate how many passages in the row, how many in the base sector, and how many you need for the model. Notice all inputs are integers, no angles.

Why meshing a single sector and not all at once? Because it guarantees the meshes are identical on every copy, not approximate, and you can scale the model from the base sector to any you need.

Hope the above helps.

July 20, 2018, 08:28	Transforming mesh 360 degree in CFX Pre	#1
AS_Aero Senior Member Join Date: Mar 2013 Location: Germany Posts: 357 Rep Power: 14	Hi I am trying to mesh a rotor body which is having 20 blades and its a huge geometry. So I was thinking if its a good idea to cut only a small wedge from the geometry and then transform the mesh in CFX Pre using rotation option. But some people told me its not a good way to do and it might create problem for the simulation. Can someone tell me if its a right way to do and will there is be any issue by doing so ?

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July 20, 2018, 09:55		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,815 Rep Power: 32	The standard practice in turbomachinery is to mesh a single passage/sector of the geometry whenever there is true geometric periodicity Then replicate the "base sector" to as many copies needed for the model. Some models may only need one sector, some two sectors (Fourier Transformation for example), or more sectors (full 360). The best practice when replicating rotationally periodic sectors is to use the "Turbo Rotation" option in the Mesh Transformation. You indicate how many passages in the row, how many in the base sector, and how many you need for the model. Notice all inputs are integers, no angles. Why meshing a single sector and not all at once? Because it guarantees the meshes are identical on every copy, not approximate, and you can scale the model from the base sector to any you need. Hope the above helps.