A numerical model for heterogeneous and confined debris flows

摘要

The flow equation for a uniform debris flow can be obtained, analytically, from integration of the local constitutive equations only in very simple schemes, for example under the assumption of uniform solid concentration and absence of lateral walls. The flow discharges computed using these assumptions are much higher than those observed. In this paper a less restrictive solution is attempted. The fluid is assumed monophase (equal velocity of solids and fluid) and heterogeneous (solid concentration variable in the cross section). The effect of the mixture heterogeneity is described, and for a monophase fluid the constitutive parameters are expressed as a function of local solid concentration. A computational code has been implemented for estimating the concentration and velocity distribution in the cross section. The code is applied to a viscoplastic (Herschel-Bulkley) mixture.