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Roughness has no influence on results, k-epsilon

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Old   June 11, 2010, 03:12
Default Roughness has no influence on results, k-epsilon
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Robert Safar
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I try to modelling flow over a small dam (embankment). The rougness of dam surface is about d90=20mm (grain size). I tried to model smooth wall and rougnesses hs= 0, 10, 20, 30, 40, 50 mm.
In this case i have these problems:
1. different results between smooth wall and rough wall hs=0mm
2. For rougneses hs higher than 20 mm is no influence on results (water level - head is constant)
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Old   June 14, 2010, 07:21
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1. There was a problem with mesh thickness.
2. Ok it's my fault. I didnt know that the first cell of mesh must be twice higher than rougness.
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