Incipient Motion Criteria for a Rigid Sediment Grain on a Rigid Surface

Criteria for the incipient motion of a rigid body initially resting on a rigid surface are formulated from first principles in this work. A modified Coulomb friction model and an associated distribution of reaction forces are proposed. There exists a surprisingly large category of general motions, however, which subscribe to a more conventional analysis; an analysis made possible by identifying so-called ``significant reaction surfaces''. In this way a model which caters for the majority of combined translations and rotations is devised. Some introductry results demonstrate the accuracy with which fluids can be numerically modelled for the purposes of entrainment. This work is an extension of previous work by the same author.