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[Other] How to estimate y+ and set cell division for K-epsilon turbulence model in openFOAM? |
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December 23, 2014, 23:29 |
How to estimate y+ and set cell division for K-epsilon turbulence model in openFOAM?
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#1 |
Senior Member
Mominul MuKuT
Join Date: Mar 2009
Location: Bangladesh
Posts: 124
Rep Power: 17 |
Good morning all!
As I told earlier about my simulation in a wind tunnel. I am expecting separation in the diffuser region, to get expected separation proper cell division is necessary. For standard k-e turbulence model I learned from the previous replies that it better to use y+>30. I have found these two sites to calculate y+ http://www.pointwise.com/yplus/ http://www.cfd-online.com/Tools/yplus.php Here is my simulation domain: Straight section height is 200mm which is 630mm long and a diffuser section with 20deg inclination having a length of 250mm. In the above two y+ calculation site, there is a term boundary layer length and reference length, I am confused with these two term because both sites calculates the same but they mention these terms differently. Shall I use this length as 200mm? But in diffuser section these vertical height is a varying height, as it has 20deg slope in bottom wall. BR MuKuT |
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December 31, 2014, 17:58 |
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#2 |
Senior Member
anonymous
Join Date: Aug 2014
Posts: 205
Rep Power: 13 |
Using adimensional parameters is just a way of having a first idea of the magnitude of magnitudes such as yplus. Use the total length of your domain and once you run the simulation use the tool named yPlus in openfoam to know exactly the value of yplus
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February 4, 2015, 05:37 |
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#3 |
Senior Member
Mominul MuKuT
Join Date: Mar 2009
Location: Bangladesh
Posts: 124
Rep Power: 17 |
Thanks a lot. I am using k-omega-SST model instead of K-E now to get more realistic separation as it was found during experiment. In preliminary stage new simulation gives better result than K-E model.
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cell division, mesh and grid, openfoam, yplus |
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