Velocity Reversal Criterion of a Body Immersed in a Sea of Particles
Abstract
We consider a rigid body colliding with a continuum of particles. We assume that the body is moving at a velocity close to an equilibrium velocity V∞ and that the particles colliding with the body reflect diffusely, that is, probabilistically with some probablility distribution K. We find a condition that is sufficient and almost necessary that the collective force of the colliding particles reverses the relative velocity V(t) of the body, that is, changes the sign of V(t)-V∞, before the body approaches equilibrium. Examples of both reversal and irreversal are given. This is in strong contrast with the pure specular reflection case in which only reversal happens.
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