Evolution of downsized crescent-shaped dune in wind tunnel experiment

The migration of a downsized crescent-shaped dune was investigated in a wind tunnel experiment. Quantified upwind influx and vertical oscillation of the sand bed were introduced to modulate the saturation level of the sand flux above the dune surface to affect dune evolution. The evolution was recorded by top-view photography and then abstracted as the evolution of self-defined characteristic quantities using a digital image processing algorithm. The results showed that, in contrast to the case for spanwise quantities, the evolution of streamwise quantities corresponds to a linear increase in the modulation magnitude more positively and in a monotonic and convergent manner. In contrast with quantities on the windward face, the changes in quantities with respect to the horns were nonmonotonic with time and almost uncorrelated with the variation in modulation strength, which reveals the distinctiveness of leeside evolution.