Title: Experimental Study of Channelization in Cohesive Granular Media due to Sub-Surface flows

Author (Talk): VIKRANT YADAV, CLARK UNIVERSITY

Abstract:

We discuss experiments where channels form in a quasi-two dimensional bed of consolidated cohesive granular particles by fluid flow. An erodible porous medium composed of millimeter scale grains and Bentonite clay was prepared in a Hele-Shaw cell. Bentonite clay is used as a cohesive binder to get better control on volume fraction of porous material. The grain fluid interaction can lead to various patterns depending on volume fraction of porous material. At sufficiently low volume fractions (<0.46) we observe formation of channels mostly due to advection of loose beads. At intermediate volume fraction (>0.46) we observe large scale rearrangement of material leading to formation of Taylor-Saffman kind of instabilities. At even higher volume fraction (about 0.59) we see material failing locally like a plug due to excessive pressure buildup. We will discuss the measured integrated rates of erosion as well as the statistical development of heterogeneity as a function of binding strength and consolidation of the medium. We also explore changes in shape of channel as a function of binder concentration.