Author(s)

T. Faug, B. Chanut & M. Naaim

Abstract

The present paper deals with the hydrodynamic force from granular streams overflowing a wall-like obstacle. An analytical continuum model is proposed to derive this force both for steady and unsteady flow conditions. The force derived from the continuum model is successfully compared to the time-averaged force from discrete numerical simulations of free-surface granular flows down an incline and overflowing a wall. A good agreement is found in a large range of slope inclinations from a slow dense regime to a rapid dilute one. The continuum model gives the various contributions of the total force. Application to avalanche dam design is discussed. Keywords: granular avalanche, protection dam, obstacle, force, continuum model, discrete simulations. 1 Introduction Gravity-driven mass movements such as dense avalanches of granular snow can lead to huge damages on structures (buildings and protection dams). The flow- obstacle interaction is a crucial question to better understand the influence of obstacles on flows of granular fluids and the force that granular fluids can exert on the obstacle. In this paper, an analytical continuum model is proposed to derive the force from avalanches overflowing a wall-like obstacle. The model is based on momentum and mass conservations applied to a control volume which corresponds to the upstream volume disturbed by the presence of the obstacle. Small-scale discrete numerical simulations on granular flows down an incline and meeting a wall were carried out to calibrate and test the continuum model. Steady

Keywords

granular avalanche, protection dam, obstacle, force, continuum model, discrete simulations