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July 29, 2009, 22:01
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equivalent sand roughness height
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#1 |
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Member
LSC
Join Date: May 2009
Posts: 58
Rep Power: 16  |
Hi, I am trying to model roughness which I only have the average grain size (0.25mm). How to I convert this value into equivalent sand roughness height? Is there any relationship?
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August 3, 2009, 22:15
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#2 |
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Member
Yi-Lang Chen
Join Date: May 2009
Posts: 58
Rep Power: 16 |
Dear LSC :
Did you simulate open channel on CFX? According your problem that you can use Parker(1991) Ks (sand roughness height)=6.0*D50(average grain size). I use the equation to decide roughness height when I simulated open channel. If you have any question, welcome to discuss with me. |
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December 23, 2012, 11:26
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equivalent sand grain roughness
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#3 | |
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Senior Member
hamed
Join Date: Apr 2009
Posts: 148
Rep Power: 17 |
Quote:
i am having same problem in sand grain roughness but in pipes .i know e/d equal to 0.001 and i dont know the right equvalent sandgrainroughness .do yo have any idea how to define it? |
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December 23, 2012, 12:50
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#4 |
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Senior Member
Christoph
Join Date: May 2011
Location: Germany
Posts: 182
Rep Power: 17 |
take a look at the cfx-solver theory guide, chapter 2 "modeling flow near the flow"/"treatment of rough walls"
http://www1.ansys.com/customer/conte.../cfx/xthry.pdf |
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