Key points are not available for this paper at this time.
Particle size-segregation can have an important feedback on the bulk flow of geophysical granular avalanches. As a polydisperse material travels downhill the larger particles rise to the surface, where they are preferentially sheared to the flow front. This coarse-rich region experiences a greater resistance to motion and the large particles are shouldered aside to form lateral levees. Wider flows may break down into a series of these lobate, ‘finger-like’ structures. In either case, the static leveed regions channelise the finer, more mobile interior, causing the resulting run-out distances to be significantly enhanced. Modelling segregation-mobility feedback effects is therefore crucial for hazard mitigation. A new class of depth-averaged continuum models is introduced that describes the transport of large particles as well as the granular rheology. The feedback arises from a basal friction law that is composition dependent, implying greater friction where there are more large particles. Numerical simulations are used to show the spontaneous formation of leveed fingers.
Baker et al. (Fri,) studied this question.