Unconfined flow of granular avalanches along a partly curved surface. II. Experiments and numerical computations

Abstract
In this paper the agreement between laboratory experiments performed with three-dimensional granular avalanches moving along a partly curved surface and their numerical predictions shall be examined. First, the most important elements of the theory describing the flow of a cohesionless granular material down a rough bed are presented. Based on the depth-averaged model equations, an advanced numerical integration scheme is developped by making use of a Lagrangian rep­resentation (i. e., the grid moves with the deforming pile) and a finite difference approximation that handles the numerically two-dimensional problem accurately. Second, experiments are described that were conducted with a finite mass of gran­ular material moving down, respectively, an inclined plane and a surface consisting of an inclined and a horizontal plane connected by a curved transition area; the initial geometry of the avalanche is generated by a spherical cap. Third, for a number of different experiments a comparison is carried out between the exper­imentally determined positions of the granular avalanche during its motion and the numerical prediction of these positions. It shows that the numerical results fit the experimental data surprisingly well.