Particle Dynamics in Sheared Granular Matter

Abstract

The particle dynamics and shear forces of granular matter in a Couette geometry are determined experimentally. The normalized tangential velocity $V\left(y\right)$ declines strongly with distance $y$ from the moving wall, independent of the shear rate and of the shear dynamics. Local rms velocity fluctuations $\delta V\left(y\right)$ scale with the local velocity gradient to the power $0.4\pm 0.05$. These results agree with a locally Newtonian, continuum model, where the granular medium is assumed to behave as a liquid with a local temperature $\left[\delta V\right(y){]}^2$ and density dependent viscosity.