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[ICEM] Octagonal Wind-Tunnel Model Replication mesh

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Old   August 6, 2013, 00:07
Exclamation Octagonal Wind-Tunnel Model Replication mesh
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Hello CFDOnliners,

I am trying to generate a hexahedral mesh for an octagonal wind-tunnel test section and there are two distinct features which make it especially difficult. The floor includes a ramp which has an incline, a platform and then a decline (CAD Images attached). This was successfully meshed using ICEM and a simple 3D blocking strategy however, I also want to include a Vortex-generator on top of the ramp and this is what makes the entire domain very challenging to block with the techniques I currently know.

The main issue is that the angular faces of the tunnel were initially blocked with Y-grids. However, once the VG is mounted in the middle and all the blocks are split around it for mesh refinement, there are wedges, non-conformal and overlapping geometries produced along the bottom edges of the tunnel and the ramp. The Y-grid for the VG and the tunnel work in isolation but once I combine them I couldn't even generate .uns or a .msh.

This is really urgent and I need to have this completed by the end of the week. Please provide some guidelines or a sample block on the geometry provided and I will really appreciate this. I attached the .tin and .igs files.

Best regards,
Attached Images
File Type: jpg InterfaceAngle1.jpg (90.3 KB, 30 views)
File Type: jpg InterfaceAngle2.jpg (97.6 KB, 27 views)
File Type: jpg AWT_VGRamp_Screen.jpg (25.9 KB, 31 views)
Attached Files
File Type: zip Ovi-AWTVGMeshing.zip (11.3 KB, 6 views)
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Old   August 6, 2013, 10:23
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I attached some images to highlight what the blocking and mesh structure was like, prior to the mounting of the VG. This is just the ramp in the tunnel and a full hexahedral mesh was possible by using the Y-grid blocking technique around the perimeter for the angled sides of the tunnel.
Attached Images
File Type: jpg WithoutVG.jpg (94.3 KB, 19 views)
File Type: jpg Capture.jpg (94.1 KB, 16 views)
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Old   August 6, 2013, 20:08
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you could have used a blocking topology without y-grid: initialize block, create an o-grid, and add two horizontal splits and two vertical splits... that being said your VG mounted is really disturbing. take a look at my blocking, i hope you or someone else can modify it and make it better.

https://dl.dropboxusercontent.com/u/...TVGMeshing.rar
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Old   August 8, 2013, 08:44
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@Crank-Shaft

I didn't check your's and diamondx topology but I didn't use any O-grid. Rather I made two horizontal and three vertical splits in the main block and another two vertical splits and a single horizontal split around "vortex-generator". And ofcourse some vertices were merged and insertion of Y-block,

Hope you have understood it
Attached Images
File Type: jpg 1.jpg (44.9 KB, 25 views)
File Type: jpg 2.jpg (44.7 KB, 19 views)
File Type: jpg 3.jpg (51.7 KB, 21 views)
File Type: jpg 5.jpg (83.8 KB, 19 views)
File Type: jpg 6.jpg (82.0 KB, 18 views)
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Old   August 8, 2013, 08:59
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Find the project files in the attached folder.
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File Type: zip Ovi-AWTV_cfd seeker.zip (41.4 KB, 12 views)
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Old   August 8, 2013, 11:04
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Thanks you very much for replying to this guys. I desperately need to find a suitable blocking strategy before the weekend.

Cfd Seeker I have modified some of the blocks slightly but used the same strategy as yourself. It seems to work well for this domain since I am not really concerned about the flow resolution near the outer walls, but rather close to the VG itself and the ramp. I attached the screenshot of side view during the pre-meshing phase to show the node bunching.

I really appreciate these responses guys. I am still curious as to what went wrong in my first attempt. If I am not mistaken it should be possible to index control and focus on the central rectangular tunnel section separately from the angled sides and hence create three distinct regions along the length of the tunnel.
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File Type: jpg Capture.jpg (79.1 KB, 21 views)
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