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sediment scour_static friction coefficient and surface roughness

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Old   November 8, 2018, 04:32
Unhappy sediment scour_static friction coefficient and surface roughness
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leang
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Dear all seniors,

I am a fresh researcher and I am simulating local scour downstream of hydropower station and the result is unacceptable. I use 4 mesh blocks (complex geometry) with 0.5cm cell size (packed sediment mesh block was set to 2cm)and the number of total cells is about 3 million. My sediment grain size is 0.2cm is simulated using Nielsen equation(default shields critical number 0.05). For boundary condition, I set the left, the right and the bottom as the wall, the upside as specific pressure and the intersection of each block as symmetry.
I see the warning of non-input the value of static friction coefficient and surface roughness of component and packed sediment.

- is it necessary to input the value of static friction coefficient and surface roughness of component and packed sediment?
- what should I pay attention?
- if shields critical number should be improved, how should I calculate shields critical value of the complex geometry?

I am waiting for your comment and hope you kindly share some experiences. I truly appreciate any recommends.

sincerely,
leang
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