On the Transfer of Heavy Particles by Intense Winds

The nonlinear problem of the acceleration of heavy particle picked up by a fast flow in a gravity field is studied analytically. This problem is interesting, in particular, in connection with dangerous convective phenomena in the lower atmosphere (heavy wind gusts, tornadoes). Heavy particles/objects carried by intense winds are one of the main hazards associated with such phenomena. The corresponding theoretical problems are complicated by the nonlinear dependence of the hydrodynamic resistance on the velocity of the particle relative to the medium, and were studied, as a rule, by numerical methods. The paper considers an analytical model that makes it possible to establish some general regularities of particle acceleration in the non-stationary flows. According to the solutions derived, the characteristic time of the acceleration of a particle during a fast intensification of the flow is an order of magnitude of the ratio of the particle settling velocity in the gravity field to the acceleration of gravity.