Computer simulation of aeolian sand ripples and dunes

A discrete computer method, which considers the principal characteristics o f the motion of discrete particles caused by the airflow over the aeolian b edforms using a set of simple rules, is suggested to simulate the initiatio n and evolution of wind blown sand ripples and dunes. The results indicate that, if the grain-bed impacting and surface creep are taken into account, the model is capable of reproducing sand ripples vividly, and describing th e reparation of any destroy to rippled surface, a phenomenon observed in fi eld. lf the saltation driven by the main flow and the secondary flow, the s urface creep due to gravity, and the slide occurring when the slope of sand surface is larger than the angle of repose are considered, the model can s imulate the formation and development of sand dunes whose shape and arrange ment in space are in accordance with the landscape of typical deserts. Afte r a further investigation into the simulation process, we draw the conclusi on that the aeolian bedforms is a system of self-organization and hierarchy with a fractal character. (C) 2001 Published by Elsevier Science B.V.