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[ICEM] Structured multi-block mesh non-smooth

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Old   June 11, 2022, 02:38
Default Structured multi-block mesh non-smooth
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S Ram Kumar
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I am working with ICEM-CFD for structured grid generation and output to CFL3D solver format.

Shown below is the rectangular 2D domain of a no-slip viscous plate in the bottom horizontal with a wedge like shock generator (SG) in the middle of the domain.

Currently, I have split the domain into 4 blocks as shown. The issue I am facing is the grid lines originating from the sharp leading edge of the SG are splitting and diverging into a triangular non-smooth appearance. Pic attached of pre-mesh. The issue is present even at the rear of the SG with the grid lines emerging from the two points diverging non-parallel to each other.

I totally want to avoid this, and want to keep a smooth structured grid with rectangular cells to the maximum extent possible. Please help, I don't know which feature to use to obtain a proper grid. The proper grid from a similar case study is shown below.
Attached Images
File Type: png geometry.PNG (9.1 KB, 18 views)
File Type: jpg blocks_diverging pre-mesh.jpg (26.4 KB, 18 views)
File Type: jpg pre-mesh_coarse.jpg (41.4 KB, 17 views)
File Type: jpg fig_ideal mesh_nasa.jpg (86.3 KB, 16 views)
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Old   June 12, 2022, 15:22
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Sebastian Engel
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Use the Extend Splits feature.
Blocking > Split Block > Extend Splits, use All and apply.

Since you have split only a selected block, but not all (valid practice here), some edges are created implicitly to maintain a valid grid structure. With extend splits, you can unmask those edges. This action will allow you to regain the bunching control on the far field edges.

Add.: You might need to collapse a block on the (likely) upstream side. It seems there is a triangular, degenerated block.

Last edited by bluebase; June 12, 2022 at 15:24. Reason: Addtitum
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Old   June 17, 2022, 01:56
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I think it would be just to move the vertices in both downstream and upstream should do the trick, just move it in the z direction and eye ball it to be straight as possible (not recommended but it gets the job done).

Final thing is the collapse block in the upstream I think are necessary as bluebase mentioned.

Best regards
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Old   July 10, 2022, 03:15
Default Structured multi-block mesh non-smooth
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S Ram Kumar
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thanks to both, bluebase and lucky. I did give it a try once, but there seems to be atleast some level of such triangular blocks, owing to the two vertices that automatically get generated because of the shock generator. I have merged the two vertices into a single point by association. I hope this was what you had meant.
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diverging grid lines, icem 18.1, meshing 2d, meshing algorithms, non-smooth transition

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