A New Algorithm for Bank-Failure Mechanisms in 2D Morphodynamic Models with Unstructured Grids

Bank failure is an important phenomenon in geomorphic processes. In the presence of river banks or steep bedforms, collapse mechanisms induced by the water-level rise deeply affect the bed evolution along with the sediment-transport processes. In this paper an algorithm capable of simulating such mechanisms in a two-dimensional two-phase morphodynamic model is presented. A mixed Cell-Centered and Node-Centered Finite-Volume discretization, which makes use of an unstructured triangular mesh and allows the slope in each cell to be univocally defined, is proposed. The geo-failure operator guarantees that when in the cell the bed slope exceeds a critical angle, the corresponding bed material and pore water will become part of the bed transport and will then follow the dynamic equations of the two-phase flow. The algorithm effectiveness is shown by the numerical reproduction of some experimental tests from the literature.