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-   -   Urgent help needed for meshing in GAMBIT (https://www.cfd-online.com/Forums/fluent/30262-urgent-help-needed-meshing-gambit.html)

 John September 3, 2002 12:38

Urgent help needed for meshing in GAMBIT

I am currently modelling airflow around a building with fins to simulate corridors. My domain size is in meters 150L x 50H x 50W and the building i am modelling is 100L x 32H x 12W. 3 pair of fins are located at both sides of the building, namely 2.5m above ground, 13.5m above ground and 29.5m above ground. Each fin has dimensions 100L x 0.2H x 2W. I need at least 4 nodes to be on the width of each fin as I am studying flow along the corridors. How do I mesh such that the fins have a higher mesh density than the domain? i.e. mesh on fins defined by interval size of 0.5 and mesh on domain and building defined by interval size of 1? If I use the subtracted volume, it seems that I could only use 1 interval size for volume mesh. Also, which mapping scheme is recommended for the fins and domain? Urgently seek help from everyone, thanks!

 sri September 3, 2002 13:16

Re: Urgent help needed for meshing in GAMBIT

Hi John,

Having different mesh densities in your domain can be done by either following any of the stratigies :

1)Use a sizing function

2)Create a duplicate face intentionally so that different mesh intervals can be given on each face.

hope this helps you,

sri

 John September 3, 2002 23:25

Re: Urgent help needed for meshing in GAMBIT

Hi Sri,

Thanks for replying :). I am currently employing this method:

1. Create geometry for domain, building and fins. Thereafter I unite the fin volumes with the building volume, and then subtracted this united volume from the domain volume.

2. I edge meshed the remaining volume using interval sizes of 1 (x direction), 0.1 (y direction) and 0.2 (z direction.

3. It seems that gambit is taking a long time to mesh the volume as the value stays at 10 percent meshed..has gambit hanged?

4. Is there any better way to mesh this volume? Wld appreciate some recommendations :) Thankss!!!

John

 anna September 4, 2002 09:08

Re: Urgent help needed for meshing in GAMBIT

After volume substractions, check for vertices, edges and face connectivity.

Instead of meshing edges using number of intervals, use interval count where you will more clearly see the node position and density. You can try to use different edge meshing schemes to get different mesh density in particular areas (your fins, surrounding walls etc.) You can also try to cut your final volume into several ones in such a way to be able to use cooper-scheme for volume meshing, meaning your subvolumes should have base faces for projections (surface mesh -pave scheme), and side faces (surface mesh - map or submap). Try to eliminate (by merging) small edges you may have.

You may get very big volume mesh for that large model, but carefully chosen edge and face mesh sizes should give you reasonably large volume mesh.

anna

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