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January 27, 2011, 03:33 |
__Backward Facing Step simulation problems__
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#1 |
Senior Member
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Dear Foamers,
I have simulated backward facing step with LES model. i created geometry with 200,000 grid. it is 3D with cyclic B.C for front and back walls. inlet conditions (U and k) are set same as Driver & Seegmiller paper. outlet pressure is set zero. I don't understand why: 1- Minimum pressure is -278 m2/s2. as you know it means -278000Pa. it is -2.78 Bar but it is not real to have less than -1 Bar. 2- Reattachment point should be near x=6H which H is step height. but it is more than 11 H in this simulation. what is the problem? Attachments are P and U contours. Thanks in advance, |
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February 11, 2011, 16:20 |
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#3 |
Senior Member
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inlet velocity turbulence was 0% in above snapshots. i changed it to 10%. So reattachment point becomes 8.5H instead of before 11H. H is step height. In Driver & Seegmiller reattachment should be 6H. i used LRR.
Changing inlet turbulent doesn't lead to desired one. What should be changed? Any help will be appreciated. |
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