Physical and numerical modelling of solid particles transport in a settling tank

The validation of the eulero-lagrangian model TRAPS in a complex flow is presented. TRAPS is based on the calculation of particles trajectories. The local instantaneous velocity field is rebuilt with the help of a random process taking into account not only the Reynolds tensor but also the lagrangian correlations. Simulations of a great number of trajectories allow to have quantitative results. Experimental data were obtained in physical models of settling tanks consisting of a sloping backward facing step and an outlet weir. The experimental study carried out with different sand samples for different geometries and discharges allowed to determine outgoing percentages and the repartition of sedimented particles. Some guidelines for the optimal dimensions of the settling tank could be given. Experimental results were mainly used for comparison with the simulations of TRAPS. A good agreement has been obtained.