MECHANICS OF AEOLIAN SALTATION AND VELOCITY PROFILE OF WIND WITH EQUILIBRIUM BLOWN SAND

摘要

The motion of blown sand constitutes an interrelating system where individualrnparticles' motion is driven by wind while it affects the turbulent structure of wind.rnThe purpose of this study is to clarify the particle/fluid interaction, and to deduce therncharacteristics of blown sand and wind reasonably based on the multiphase flowrnmechanism.rnIn this study, the motion of individual particles are calculated under clear windrncondition (wind without blown sand), and then the turbulent structure of wind withrnblown sand is re-calculated. Furthermore, the motion of blown sand is recalculatedrnunder the condition of wind with blown sand. The calculation is repeated to obtainrnan equilibrium state of wind with blown sand. By this scenario of calculation, thernturbulent structure of wind with blown sand and the characteristics of blown sandrn(transport rate, concentration distribution and so on) are simultaneously evaluated.rnFor the phase of particle motion, the repulsion of a saltating particle on the bed tornmaintain successive saltation is important, and a simple stochastic model isrnemployed. While, for the phase of flow, the change in profile of the Reynolds stressrnis a key, and velocity profile is obtained by assuming a simple mixing length model.rnThese simplified models may have other alternatives, but such a simplificationrnmakes the particle/fluid interaction clear in this paper.