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November 17, 2016, 14:27 |
prism layer or not?!
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#1 |
Senior Member
SinaJ
Join Date: Nov 2009
Posts: 136
Rep Power: 16 |
Hi,
I'm trying to simulate the water flow in a huge tank (diameter: 20m) with an inlet of 5m*5m (of course turbulence!) . So should I even consider prism layer for such a flow? I'm ok with having prism layers, but I realized that it makes the convergence much worse (specially in multiphase with mixture model). PS: considering that the boundary layer for such a flow would be something around 10cm, or even less. Thanks |
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November 18, 2016, 16:16 |
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#2 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,674
Rep Power: 65 |
If you have a no-slip boundary condition, then I highly recommend it. If however you have a slip condition, then no.
The biggest thing about prism layers is that wall adjacent cells are parallel to the wall and this helps prevent really stupid things from happening (like velocity vectors that go into the wall). Convergence problems with prism layers is most likely mesh quality issue. Automated meshers tend to have difficulty with prism layer generation. But you have no excuse for going into a simulation with a bad mesh, unless your geometry is really really complicated! If you want good results, make a nice mesh. |
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November 18, 2016, 16:32 |
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#3 | |
Senior Member
SinaJ
Join Date: Nov 2009
Posts: 136
Rep Power: 16 |
Quote:
BTW, let me explain how I mesh, maybe you could kindly recommend a better way: using ICEM, tetrahedral everywhere. One layer of prism layer with thickness of ~15cm. Splitting that single layer to 12 layers with size ratio of 1.1 or 1.2 PS: Unfortunately I'm not allowed to share the geometry. |
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November 21, 2016, 08:09 |
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#4 |
Senior Member
Kushal Puri
Join Date: Nov 2013
Posts: 182
Rep Power: 12 |
Y+ = 30 m good, can proceed with standard k-epsilon turbulence model
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