HEAT TRANSFER MEASUREMENTS IN NEUTRALLY BUOYANT SUSPENSIONS IN THE INERTIAL REGIME

The present study experimentally investigates the behavior of thermal diffusivity of a sheared granular suspension with neutrally buoyant particles. The study uses a Taylor-Couette cell with a rotating outer cylinder and fixed inner cylinder to create a uniform shear flow while suppressing fluid turbulence for lower Reynolds numbers. Spherical PMMA beads of 2 mm were used to make a suspension with a glycerol-water mixture as the base fluid. For a small fixed volume fraction of 5%, changing the rotation speed, and therefore the shear rate, particle Reynolds numbers are varied from 0-30, going from Stokes flow to timedependent flow with increasing inertia. We study the thermal diffusivity of the suspension by examining the decay of the inner wall temperature after a sharp thermal pulse. The thermal diffusivity is extracted from the observed temperature decay using a model for one-dimensional diffusion into the particle suspension. A non-monotonic behavior of thermal diffusivity with volume fraction is observed.