TY - JOUR

T1 - Liquid redistribution in sheared wet granular media

AU - Roy, Sudeshna

AU - Luding, Stefan

AU - Weinhart, Thomas

PY - 2018/11/19

Y1 - 2018/11/19

N2 - Shearing wet granular systems causes a redistribution of the interstitial liquid, which can affect the material's bulk behavior. Using the discrete-element method, we study the early rapid transients, the intermediate states, and the slow long-term evolution of liquid redistribution for various material parameters and different initial wetting conditions in an inhomogeneous split-bottom ring-shear cell featuring a wide shear band away from the system walls. In our model, liquid exists in two states, either in liquid bridges between particles or in liquid films on the particle surfaces. Under deformations like shear, the liquid is redistributed due to the rupture of existing and formation of new liquid bridges. Since we assume the immediate redistribution limit as a new model parameter, a liquid bridge limit volume is imposed to avoid extensive clustering of liquid. Studying the effect of the local shear rate on the liquid redistribution, two distinct effects are observed: For small amounts of shear, i.e., small strain amplitude, the interstitial liquid is randomly redistributed locally, and for larger amounts of shear, liquid is transported away from the shear zone. The local redistribution quickly results in a characteristic probability distribution of liquid bridge volumes, independent of the initial wetting conditions, but the mean and the shape of the distribution are dependent on the limit volume. Although the shear-driven diffusion-like liquid transport is active from the beginning, it dominates the transport in the long term, when the liquid moves out of the shear band, making the shear band dry. Ongoing theoretical analysis suggests a competition of drift and diffusive mechanisms in a different set of coordinates that can explain all our observations by defining a local Péclet number that quantifies the relative strength of the two transport mechanisms.

AB - Shearing wet granular systems causes a redistribution of the interstitial liquid, which can affect the material's bulk behavior. Using the discrete-element method, we study the early rapid transients, the intermediate states, and the slow long-term evolution of liquid redistribution for various material parameters and different initial wetting conditions in an inhomogeneous split-bottom ring-shear cell featuring a wide shear band away from the system walls. In our model, liquid exists in two states, either in liquid bridges between particles or in liquid films on the particle surfaces. Under deformations like shear, the liquid is redistributed due to the rupture of existing and formation of new liquid bridges. Since we assume the immediate redistribution limit as a new model parameter, a liquid bridge limit volume is imposed to avoid extensive clustering of liquid. Studying the effect of the local shear rate on the liquid redistribution, two distinct effects are observed: For small amounts of shear, i.e., small strain amplitude, the interstitial liquid is randomly redistributed locally, and for larger amounts of shear, liquid is transported away from the shear zone. The local redistribution quickly results in a characteristic probability distribution of liquid bridge volumes, independent of the initial wetting conditions, but the mean and the shape of the distribution are dependent on the limit volume. Although the shear-driven diffusion-like liquid transport is active from the beginning, it dominates the transport in the long term, when the liquid moves out of the shear band, making the shear band dry. Ongoing theoretical analysis suggests a competition of drift and diffusive mechanisms in a different set of coordinates that can explain all our observations by defining a local Péclet number that quantifies the relative strength of the two transport mechanisms.

U2 - 10.1103/PhysRevE.98.052906

DO - 10.1103/PhysRevE.98.052906

M3 - Article

VL - 98

JO - Physical review E: covering statistical, nonlinear, biological, and soft matter physics

JF - Physical review E: covering statistical, nonlinear, biological, and soft matter physics

SN - 2470-0045

IS - 5

M1 - 052906

ER -