Sand Influx Effect on Barchan Steady-state Profile

In this study, based on the crest line model, a differential equation-based mathematical approach to dune dynamics, we investigate the effect of non-contact interactions between barchans through sand flow on their morphodynamics, which is a largely unexplored topic. Numerical calculations reveal the following: (i) When sand flows into a single point along the upwind slope of a barchan, the central axis aligns with the sand inflow point. Consequently, the profile of the barchan develops a sharper, pointed steady shape in the front view and a slightly deformed parabola in the top view. (ii) When sand flows into two points, the initial barchan splits into two. This division depends on the inflow amount and distance between the sand influx points. In addition, under a one-point sand inflow, the analytical solution supports the numerical results and provides an explicit mathematical expression of the crest line in the steady states. These results provide new insights into the spatio-temporal dynamics of barchans in desert areas with active interdune sand flows and further our understanding of the complex dynamics of barchan collisions.