ABSTRACT
This chapter tackles the general problem of the force exerted by a mudflow on an immersed body. It focuses on the force exerted by a steady mudflow around a totally or partially immersed obstacle. The chapter presents some theoretical considerations concerning the impact force of transient mudflows or muddy debris flows on an obstacle. It also focuses on the simplest problem of a body immersed in a flow which is uniform sufficiently far from the body. Various experimental results have been obtained which aimed at determining the drag force of a uniform flow around a sphere. In the frame of reference of the sphere the velocity distribution is antisymmetrical with regard to sphere centre. An excellent literature review and critical analysis of the problem of drag force exerted by yield stress fluids on a sphere was done by R. P. Chhabra and P. H. T. Uhlherr.
