Resistance Rule of Mud Flows on Movable and Fixed Beds

A nondimensional parameter governing debris and mud flows and dry-grain flow is derived from the comparison between intergranular-stress and inertia terms in the momentumu equations. From the result nondimensional distance from the bed is introduced for velocity profile of these flows. Granular and inertial sublayers are found to exist near the bed in the flows. The former sublayer has linear velocity profile due to the major role of intergranular stresses, while the latter sublayer has logarithmic velocity profile due to the inertial forces. Nondimensional surface velocityus/u*and average velocityu/u*are calculated and the results are compared with the experimental ones.