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Old   June 15, 2005, 00:11
Default 2D and 3D Problems
  #1
Soon
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Hi,

Hope any CFX experts could give me some advices on my problems and any comment is appreciated. Thanks

My 3D model managed to simulated and get a good/expected results from CFX. But, while I changed the Mesh to 2D-extrude Mesh, the results came out farly that I expected.

I used the same turbulence model, boundary condition setups. But, both the 2D and 3D results has much differences.

Please Help ME~
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Old   June 15, 2005, 18:46
Default Re: 2D and 3D Problems
  #2
Glenn Horrocks
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Hi,

I assume a 2D model is a good representation of the flow, so the reduction in accuracy is not due to 3D effects.

When generating 2D extruded meshes make the mesh extrusion length approximately equal to the shortest element edge length. This will make the solver a bit more accurate and robust.

Glenn Horrocks
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Old   June 15, 2005, 21:47
Default Re: 2D and 3D Problems
  #3
Soon
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Thanks for helping me that.

I appreciate
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Old   June 17, 2005, 06:12
Default Re: 2D and 3D Problems
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Soon
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The result from the CFX-Post is that the flow traveling alone the model (x-direction) but it's dropping down all the way in y-direction. where my z-direction is the thickness of the 2D extrude Mesh Plate.

The result i expected is the flow traveling along the x-direction.

Is there anyone know why is that happened? Thanks
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Old   June 17, 2005, 10:53
Default Re: 2D and 3D Problems
  #5
Rui
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Hi,

Is the 2D model a good representation of the real 3D problem? Why?Have you set SYMMETRY boundary conditions to the 2 surfaces perpendicular to the z-axis?

Assuming the 2D model is a good representation, if the flow is dropping down in the 2D model, it should also drop down in the 3D model.

You could give some more details of the problem you're trying to solve.

Regards,

Rui
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Old   June 23, 2005, 21:23
Default Re: 2D and 3D Problems
  #6
Soon
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Hi there, I'm trying to simulate a jet flow across an opening boundary which driven by a speaker. Therefore, a Sine equation has been input in CEL expression. Yap. i did set the symmetry boundary to 2 faces.

there have huge large differences if i applied the same flow amplitude. where, 3D could flow across the x-direction and 2D results seens to be very difficult to create the flow across the x-direction.
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