Profiles analysis of sand dunes and their steady state signification.

The distribution of wind velocity along the two fundamental profiles indicates that the convex profile of barchan and transverse dunes are in a steady state to uni-directional winds. A steady state profile having a separate crest and brink ensures a higher advance of slip-face relative to the windward slope. A triangular sharp-edged profile of seif dunes is not in a steady state under long-term perpendicular uni-directional wind. Steady state can be attained, however, by bi-directional winds of oblique approach to the dune. -from Author