AGGREGATION OF COHESIVE SEDIMENTS INDUCED BY INTERNAL SHEAR RATES WITH APPLICATION TO SEDIMENTATION

摘要

An improved model for aggregation and deposition of cohesive sediments in flowing water was formulated as a power function of the sediment concentration and the hydrodynamic forces prevailing in the water column and at the surface of the sediment bed. The aggregation mechanism was described by a removal rate coefficient and an exponent, both of which were expressed as functions of the internal shear rate, which is one of the key parameters influencing particle collisions. Comparison of model predictions with two sets of experimental data showed that the model was capable of adequately representing cohesive sediment removal from the water column. The model formulation was also incorporated into a two-dimensional, vertically-averaged finite element model of sediment transport. The depositional behavior of cohesive sediments was verified by simulating a flume experiment.