[ANSYS Meshing] Solid block inside a tunnel for smoke production (3D)

freddyflue · December 8, 2017, 16:44

I'm trying to create a good quality mesh for a problem involving smoke dispersion in a tunnel fire.

I have attached the geometry for the tunnel which includes the heat source block (a slice through the original air cavity) which is to be used later for production of the smoke. Obviously, the mesh will need to be fine around the heat source as well as the walls and ceiling and the space between the heat source and the ceiling. Due to the nature of smoke, a coarser mesh could be used at the floor of the cavity and at the outlet (the farthest away wall).

I have tried the inflation method but I can't get it right. The mesh always ends up a fine grid around the boundaries and coarse in the middle of the tunnel, where a lot of turbulence will occur.

Any advice on how to build this mesh would be greatly appreciated. I can attach more images if it helps.

Thank you for everything you do!

Gweher · December 15, 2017, 14:27

Hi Freddy,

This is quite an easy fix. You should create planes on the 5 fluid faces around the heat source. You can then slice the geometry in DM, group the resulting bodies into a single part (select all bodies in DM > rmb > form new part). You will then be able to fully "control" the mesh generation by adding edge sizing with bias to create your BL.

Have fun

freddyflue · December 15, 2017, 15:50

Hi Gwenael, thanks for the advice! I have done something similar since I made the post but still haven't found the solution. I will do as you have described above.

Something I found when I tried it my way - of course it was probably wrong: the new sub-sections in the part added a lot of boundaries in the solver (FLUENT) that I couldn't identify or define with a named selection (named wall-23, wall-45, etc for example). Most of these boundaries were "interfaces". This made setup entirely confusing!

Additionally, I couldn't properly edit the solid block as a boundary for smoke production as it was just an interface.

Are there any settings or features you think I may have missed there? Thanks again for the advice.

Freddy

Gweher · December 15, 2017, 17:03

Hi Freddy,

Well, one thing you need to pay attention to is to put all your bodies inside a single part (in DM select all the bodies > rmb > form new part). As you split your domain, you end up with sub-domains and the interfaces represent the fluid “link” between adjacent faces so that the fluid can flow in between.

If you upload your model as a workbench archive I can have a look.

freddyflue · December 15, 2017, 17:39

I can't seem to attach the file (too big) so I have put it in my OneDrive folder. Let me know if you would rather I upload it somewhere else!

https://1drv.ms/u/s!AsCvXYVS5GeotGMdTygEkcXGw2xV

You'll notice that there are so so many extra(?) boundaries if you open in the solver.

Thanks

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December 15, 2017, 14:27		#2
Gweher Senior Member Gwenael H. Join Date: Mar 2011 Location: Switzerland Posts: 392 Rep Power: 20	Hi Freddy, This is quite an easy fix. You should create planes on the 5 fluid faces around the heat source. You can then slice the geometry in DM, group the resulting bodies into a single part (select all bodies in DM > rmb > form new part). You will then be able to fully "control" the mesh generation by adding edge sizing with bias to create your BL. Have fun

December 15, 2017, 15:50		#3
freddyflue New Member Join Date: Dec 2017 Posts: 3 Rep Power: 8	Hi Gwenael, thanks for the advice! I have done something similar since I made the post but still haven't found the solution. I will do as you have described above. Something I found when I tried it my way - of course it was probably wrong: the new sub-sections in the part added a lot of boundaries in the solver (FLUENT) that I couldn't identify or define with a named selection (named wall-23, wall-45, etc for example). Most of these boundaries were "interfaces". This made setup entirely confusing! Additionally, I couldn't properly edit the solid block as a boundary for smoke production as it was just an interface. Are there any settings or features you think I may have missed there? Thanks again for the advice. Freddy

December 15, 2017, 17:03		#4
Gweher Senior Member Gwenael H. Join Date: Mar 2011 Location: Switzerland Posts: 392 Rep Power: 20	Hi Freddy, Well, one thing you need to pay attention to is to put all your bodies inside a single part (in DM select all the bodies > rmb > form new part). As you split your domain, you end up with sub-domains and the interfaces represent the fluid “link” between adjacent faces so that the fluid can flow in between. If you upload your model as a workbench archive I can have a look.

December 15, 2017, 17:39		#5
freddyflue New Member Join Date: Dec 2017 Posts: 3 Rep Power: 8	I can't seem to attach the file (too big) so I have put it in my OneDrive folder. Let me know if you would rather I upload it somewhere else! https://1drv.ms/u/s!AsCvXYVS5GeotGMdTygEkcXGw2xV You'll notice that there are so so many extra(?) boundaries if you open in the solver. Thanks