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December 4, 2015, 14:49 |
General question about SST turbulence model
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#1 |
New Member
Richard Renaud
Join Date: Mar 2015
Posts: 6
Rep Power: 11 |
I have a general question about when it is beneficial to use an SST turbulence model.
I've been reading up on turbulence lately. Prior to this recent study, I had a habit of using the SST turbulence model without checking the y-plus of my grid. For example, I used SST when modelling a cylindrical feed well with a tangential inlet pipe that contains baffles. Since there are baffles perpendicular to the flow, separation is likely to occur and I thought that SST would be a good choice to model this. However, I checked my mesh and my y-plus is on the order of 100! I am wondering, as a general question, does SST offer any advantages over a standard k-ε model when the boundary layer is not well refined. If it is computationally infeasible for me to refine the boundary layer with a y+ of 1, would you recommend that I stick with the SST model anyways? Or does the SST model offer no benefits over a k-ε model when the mesh refinement in the boundary layer is insufficient? Thanks, Richard Renaud |
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December 19, 2015, 05:13 |
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#2 |
New Member
Syed Aaquib Hazari
Join Date: Apr 2015
Location: Delft
Posts: 16
Rep Power: 11 |
Dear Richard,
If you're planning to use a grid with a large yplus of the order of 100 I suggest that you should use k-e model. Only if your yplus is less than 2 (it can extend till 4) you should use the SST or k-w model. At a wall gradients are steep and basically the SST and k-w model directly solve the equations at the grid cells. While k-e uses wall functions to solve the gradients hence less computationally expensive. Furthermore, SST is a combination of k-w and k-e. Good luck! |
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