Experimental Granular Rheology:

By uniformly exciting a granular media using a random sum of the container's elastic vibration modes, we can directly measure the speed of sound, thermal conductivity, and viscosity as a function of density and granular temperature in this uniformly heated steady state. Using a sinusoidally varying forcing we can measure the frequency dependence of the transport properties. Granular media as an analog for collective systems in extreme conditions: We will study the flow of uniformly heated granular media in a small channel as an analog for mesoscopic systems. We can explore phase transitions in systems of rods, in mixtures of rods and spheres, and in mixtures of different sized spheres. These studies will add to the understanding of both granular media and ordinary condensed matter under extreme situations including confined geometries, gradients that are large on the scale of the mean free path, and flow in which intrinsic mechanical stress can induce phase transitions.

We are currently developing new experiments in this area and applying for funding.