Fluid boundary of a viscoplastic Bingham flow for finite solid deformations

Abstract

a b s t r a c tThe modelling of viscoplastic Bingham fluids often relies on a rheological constitutive law based on a "plastic rule function" often identical to the yield criterion of the solid state. It is also often assumed that this plastic rule function vanishes at the boundary between the solid and fluid states, based on the fact that it is true in the limit of small deformations of the solid state or for simple yield criteria. We show that this is not the case for finite deformations by considering the example of a two state flow on a tilted plane where the solid state is described by a Neo-Hookean model with a Von Mises yield criterion. This opens new approaches for the modelling and the computation of the fluid state boundaries.

Dynamics of glide avalanches and snow gliding

“…Yield stress fluids have long been used to model natural materials such as debris mixtures and snow [ Johnson , ; Ancey , ]. However, this ideal situation poses theoretical problems for the slope stability problem addressed here [ Thual and Lacaze , ], and its suitability as a rheological model for debris flows has been questioned [ Iverson , ]. This model's major deficiency is the absence of general mechanism to explain how a stable layer of material becomes unstable or, to put it differently, why the yield stress decays sufficiently for the layer to yield.…”

Wall friction effects and viscosity reduction of gel propellants in conical extrusion

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