Sediment Scour model
 

I want to use sediment scour model of Flow-3D software (version 9.4.1) to model sedimentation tanks, so first I choose my sediment as Zeolite with Density=1218 Kg/m3. for the other part of simulation I have these questions:
1) If I active sediment scour model in Flow-3D, automatically the density evaluation also is activated which using this method (density evaluated as a function of other quantities) for density evaluation as default setting. Now my question is that this part (density evaluation) also have another 2 item (1- constant uniform density and 2- solve transport equation for density) and I don't know which one is suitable and should be chosen?
2) as already said I have just density and diameter of my sediment, ( Density=1218 Kg/m3, diameter= 64µm and I obtained critical shields number with the equation that put in help of Flow-3D software= 0.26439), and now I don't have any data for other characteristics of the sediment such as Drag Coff, Entrainment coff, Bed load Coff and Angle of repose and I used the amount of the default of the software. my question is that is there any relationship between the diameter or density with these parameter and how can I define these parameter more accurately? also how much is the effect of these parameter in the modeling of the sediment scour modeling?

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