Turbidity current
Hello everyone,
I am working in a lab where we make some experiments on turbidity currents, so I am trying to modelize a turbidity current with Fluent to compare the numerical results with the experimental ones. I've got some difficulties to obtain a good model which is matching with reality. I'm using fluent 14 with a simple geometry (a flume 0.580x5x0.4m or 0.580x5m in 2d) meshed with Gambit (40 000 cells approximately). I've put water in the flume. I tried to introduce a turbidity current by a velocity inlet in the left side, 0.5 m/s for velocity, 0.1 for volume fraction of sediment, and 20% for the turbulence intensity. (I also tried to patch a sediment suspension in the left part of the flume (density 2500 kg/m3) with a volume fraction of 1 then 0.4, 0.2, 0.1 with water and 20% for turbulence intensity I tried all of them. Then I've injected water by the left side, I tried different velocities 10m/s 1m/s 0.5m/s 0.1m/s 0.01 m/s). I used a pressure based transient model with gravity, and an implicit Eulerian multiphase model. For turbulence I used k-epsilon model with RNG, standard wall functions and dispersed turbulance multiphase model. Then I've put the granular option in the sediment phase with a syamlal-obrien interaction with water. When I solve this problem, I have not got the billows or just the first one in the head but not in the body. I posted some movies and pictures here : https://docs.google.com/folder/d/0B7...VEk/edit?pli=1 What I want to obtain is a model with all the billows of the turbidity current like we can see on this videos for exemple : http://video.google.com/videoplay?do...40257860282305 I tried a lot of different model, parameters, turbulence options ... and I always have an imprecise model (without the billows) so I would like to understand what is wrong with my approach. Thank you. Julien |
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