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-   -   Sediment layer for scouring problem (http://www.cfd-online.com/Forums/flow-3d/130123-sediment-layer-scouring-problem.html)

sycst911 February 20, 2014 03:49

Sediment layer for scouring problem
 
Hello everyone. I am still new to scouring simulation in Flow-3D. I have a basic question to ask, which is "How to generate sediment layer for scouring simulation?".

I have specified my initial fluid region, especially the Z minimum. Is everything below Zmin sediment? Else how do I "place"/"locate" my sediment? I know my flow depth, and I would like the sediment to be right below the flow depth. But how?

Also, an extra small question is that what does "packed sediment concentration" mean? How to actually determine the value?

Appreciate if anyone could help. Thanks! :)

m.poorjafar March 1, 2014 09:02

you must define component and select " packed sediment" in component type,then edit it in subcomponent-limiters

sycst911 March 2, 2014 20:49

Quote:

Originally Posted by m.poorjafar (Post 477422)
you must define component and select " packed sediment" in component type,then edit it in subcomponent-limiters

Thanks m.poorjafar. But I'm using 9.3 version. Probably I don't have the features you mentioned above...? o.O

m.poorjafar March 4, 2014 18:14

in this version : in "initial" , front the packed sediment, specified density of sediment, and in "limiters" specified location of packed sediment

sycst911 March 6, 2014 07:52

Quote:

Originally Posted by m.poorjafar (Post 478118)
in this version : in "initial" , front the packed sediment, specified density of sediment, and in "limiters" specified location of packed sediment

Ok.thanks.

By the way, one very simple yet "deadly" question. what is the viscosity of water at 20 degree (in SI unit)? I found out it should be 1.0E-06, but why is the default setting in Flow 3D shows 0.001? I am confused. Please help!! :(

sycst911 March 6, 2014 21:37

sorry. I have found the answer. thanks!

sycst911 March 6, 2014 21:41

My last problem remaining is that my sediment tends to be washed off too easily within seconds. I am not sure how to manipulate it despite varying all the values of "critical sediment fraction", "cohesive sediment fraction", "packed sediment concentration". Manipulating these values seem doesnt help much.. Is there any other way to make my sediment binds more tightly (higher cohesiveness)? obviously i couldnt change the sediment diameter, density, Shields parameter, etc. Please help me... :(

*Why is the angle of repose -90? I thought it is supposed to be 30 for sand, normally speaking.


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