SIMULATING STUDY ON BARCHAN DUNE

Barchan dune is one of the basic forms of eolian landform, it is usually moulded by high concentration non saturated wind sand flow. The formation process of barchan dune begins from “wave grain duality” of wind sand movement, and goes through two developmental stages of sand material accumulating (high concertration saturated wind sand flow) and dune form moulding (high concentration non saturated wind sand flow), i.e. the processes of dissipative increase and dispersive decrease. The scattered single barchan dunes on non sandy bed surface have obvious characteristics of mobility and unstability (not including barchan sand hill). The formation of barchan dune in wind tunnel (its dune scale is one order of magnitude larger than sand ripple scale) is helpful to know the formation mechanism of barchan dunes.