Electric field in windblown sand flux with thermal diffusion

Abstract

A theoretical model considering thermal diffusion (TD) from a sand bed is suggested in this paper to account for the effect of both TD and the electric field produced by charged sand grains during the evolution of windblown sand flux, where the coupled interaction among wind speeds in the vertical and the horizontal directions, sand movement (saltation, suspension, and creep), and the electric field are taken into consideration. The numerical results show that during the evolution of windblown sand flux the electric field varies along with time and height. Then the profiles of the electric field produced by charged sand grains in windblown sand flux are quantitatively analyzed in detail and are compared with those without considering TD at different moments and different heights. Also, the results indicate that different conditions would produce different electric fields in magnitude: electric fields considering TD are more intense than those without considering thermal diffusion (NTD) at the same time and height. In the meantime, when the windblown sand flux reaches steady state, the mass flux profile and the transport rate of sand grains will increase, while horizontal wind speed will decease because of the effect of TD and the electric field. Copyright 2006 by the American Geophysical Union.