# Free Surface Flow with Sediment Transport

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 April 17, 2008, 10:12 Free Surface Flow with Sediment Transport #1 M. Riffai Guest   Posts: n/a Sponsored Links Hello CFX Folks, I am trying to simulate flow over an embankment weir (small trapezoidal dam) where as the bed is mobile. I was successful in simulating the hydrodynamic part, but now I would like to include the effects of the mobile bed. So I believe it is possible to simulate the transport of sediment in three ways: 1- Eulerian-Eulerin Multiphase 2- Lagrangian Particle Transport (although CFX won't let me include two Eulerian-Eulerian models or two continuos phases like air and water with a dispersed phase like solid particles using the Lagrangian model) 3- Create a new material (water and sediment) and an additional variable such as concentration and solve a transport equation (e.g. Poisson or diffusive transport) I would like some advice on how to define each phase in each of the cases above (if possible. I have a feeling the Lagrangian Particle Transport will not work because the air and water phase cannot both be continuous wtih a dispersed solid phase. I know this has been done before, and I'm sure there is a way around it). Your help is very much appreciated. Thanks! Regards, M. Riffai

 April 17, 2008, 19:51 Re: Free Surface Flow with Sediment Transport #2 Glenn Horrocks Guest   Posts: n/a Hi, This sounds like it would be best done as a discrete element model. These type of models can account for particle size and packing, settling and motion. At the moment you need to couple to a package like EDEM to do this, but I hear that CFX V12 has some capability in this area. Not sure if it will do what you are looking for. Regards, Glenn

 December 1, 2011, 18:23 #3 New Member   Javier Climent Agustina Join Date: Nov 2011 Posts: 7 Rep Power: 7 Hello M. Riffa, Finally, how did you define this model? Option 1, 2 or 3? I'm really interested in this system. I had several problems with option 2 as well, but I think it's the best approach. I wouldn't define solid particles as a "solid dispersed". On the other hand, air and water continuous phases are necesary. Thanks a lot

 September 5, 2013, 09:45 #4 New Member   marjan Join Date: Aug 2013 Posts: 11 Rep Power: 5 HI I wanna model the pickup rate as expression mentioned by van.Rijn as follow: P=0.00033(tet-tet_cr/tet_cr)^1.5 * (s-1)^0.6 *g^0.6 *d^0.8/nu^0.2 which ni is diffusivity and s is ratio of densities and d is particle diameter. How could I nondimensional this expression and relate it to froud-Numbewr and Reynold? Thanks

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