8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Tue 611:23-14:00P9.47Rheology of dilatant fluidHiizu Nakanishi 11 Kyushu University, 10-4, Hakozaki 6, Higashi-Ku, 812-8581, Fukuoka, JapanDense mixture of granules and liquid often shows a severe shear thickening and is called a dilatantfluid. We construct a fluid dynamical model of the dilatant fluid by introducing a phenomenologicalstate variable for a local state of dispersed particles. With simple assumptions for an equation ofthe state variable, we demonstrate that the model can describe basic features of the dilatant fluidsuch as the shear stress-shear rate curve that represents discontinuous severe shear thickening,hysteresis upon changing shear rate, instantaneous hardening upon external impact. Analysis ofthe model reveals that the shear thickening fluid shows an instability in a shear flow for someregime and exhibits the shear thickening oscillation, i.e. the oscillatory shear flow alternatingbetween the thickened and the relaxed states. Results of numerical simulations are presented forone and two-dimensional systems.47