The spreading of a granular column from a bingham point of view

The collapse and spreading of granular columns has been the subject of sustained interest in the last years from both mechanical and geophysical communities. Yet, in spite of this intensive research, the adequate rheology allowing for a reliable continuum modeling of the dynamics of granular column collapse is still open to discussion. Essentially, continuum models rely on shallow-water approximation for which dissipation and sedimentation processes are taken into account through the introduction of ad hoc laws. However, the rheological origin of the experimental scaling laws exhibited by the granular columns when spreading remains unclear. On these grounds, we adopt an alternative approach consisting of studying the collapse of columns of material obeying a Bingham rheology. Therefore we carried out series of numerical simulations using the Gerris Flow Solver solving the time dependent incompressible Navier-Stokes equation in two dimensions for the specified rheology. We first check that the mass exhibit similar scaling laws as those shown by granular columns. Then we investigate in which extent rheological parameters do reflect on these scaling laws. A comparative analysis of Bingham and granular flow characteristics ensues.