Erosion of Fluid Mud Layers. II: Experiments and Model Validation

Abstract

A study on the erosion of soft mud layers caused by entrainment is reported. Experiments were carried out in an annular flume with suspensions of kaolinite and natural mud. The results of these experiments compare favorably with the results of an integral entrainment model, described in a companion paper. It can be concluded that the initial entrainment process of fluid mud is identical to the entrainment process of two-fluid systems, that is, the upper part of the fluid mud behaves as a viscous fluid. During this initial phase, the entrainment rate may be affected by the time scale for boundary layer development. At a later phase the entrainment process is hindered by the work required to keep the sediment in suspension and by the strength of the bed accounted for by treating the mud as a Bingham plastic. Values for the settling velocity, the yield strength, and the viscosity, used in the model to obtain a fair agreement with the experiments, are comparable to those obtained from independent measurements.