MECHANICS OF MUDFLOW TREATED AS THE FLOW OF A BINGHAM FLUID (NON-NEWTONIAN, KAOLIN CLAY).

摘要

A Bingham model was adopted to study the rheology and the fluid mechanics of mudflows. Mudflow was treated as the flow of a pseudo-homogeneous dispersion of solids in a non-Newtonian slurry of fine particles. A method was developed to estimate the yield stress and the plastic viscosity of mud, given the water content and the size distribution of solids.; Theories of the flow of a Bingham fluid in a wide open channel were developed. Equations for predicting the transition from laminar to turbulent flow were formulated, and verified through experiments in a 40 foot flume using kaolin clay slurry. These experiments showed that transition occurred at higher Bingham Reynolds numbers for higher Hedstrom numbers of flow.; A theory of uniform turbulent flow in a wide and smooth open channel was developed. The correlation for an empirical turbulence damping parameter was determined using experimental data. This parameter was found to be a function of both the Hedstrom number and the Bingham Reynolds number. Velocity profiles and friction factors predicted by the theory were verified with experimental data. Turbulent flow of a Bingham fluid in an open channel was found to approach the flow of a Newtonian fluid, when the Bingham Reynolds number of the flow was increased to a value such that the magnitude of the inertia forces were at least 1,000 times that of the yield forces associated with the Bingham yield stress.; A theory of turbulent flow in a rough channel was developed. Theoretically computed average velocities over the flow cross-section were verified using experimental data.; Computer programs for estimating the yield stress and the plastic viscosity of mud, and for computing uniform flow in a wide channel were developed.