Roughness has no influence on results, k-epsilon

Robert Safar · June 11, 2010, 04:12

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)

Robert Safar · June 14, 2010, 08:21

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.

June 11, 2010, 04:12	Roughness has no influence on results, k-epsilon	#1
Robert Safar New Member Robert Safar Join Date: Jun 2010 Posts: 2 Rep Power: 0	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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June 14, 2010, 08:21		#2
Robert Safar New Member Robert Safar Join Date: Jun 2010 Posts: 2 Rep Power: 0	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.