CALCULATION OF THE PRIMARY TRAJECTORIES OF DUST SEEDS, SPORES AND POLLEN IN UNSTEADY WINDS

Abstract

The movement of dust seeds, spores and pollen released into winds which fluctuate in both speed and direction is considered in terms of the aerial mechanics of a small spherical particle moving under the Stokes' law of resistance and in a gravitational field. Equations of motion are established from which the aerial paths followed may be determined whenever it is possible to specify the movement of the environment accurately and in sufficiently fine detail. Example calculations show how deposition may arise on account of wind fluctuations, in addition to the normal process of gravitational sedimentation, and how very complicated trajectory geometry can result in quite simple flows which vary in both time and in space and time. It is also shown that very different positions of ultimate migration may be occupied at a particular time by particles released from positions quite close to one another in space and into unsteady winds. Copyright © 1975, Wiley Blackwell. All rights reserved