We report on a study of advancing quasi-two-dimensional sand fronts on an inclined flat and thin strip confined between two vertical plates. These fronts form when a thin initial stream of sand running down the flat obstacle gets trapped at some distance from the injection point. Right after this trapping, the front starts to advance upstream and grow in time. The shapes at successive times are found to be self-similar in time. The stability conditions for the obtained fronts are also outlined. A simple model for interface dynamics gives reasonable predictions for the observed shapes.

• Received 22 October 2002

DOI:https://doi.org/10.1103/PhysRevE.67.010303