Stability of flows in fluidized beds

We study the linearlized stability of the state of uniform fluidization, within the context of the theory of mixtures. The mixture is assumed to be made up of a classical linearly viscous fluid infused with particles. In marked departure from most of the previous studies, we model the solid as a granular material and assume a constitutive relation that stems from classical motions in continuum mechanics. The linearized stability analysis of the state of uniform fluidization, in general, for a three-dimensional disturbance leads to an eighth order equation for the characteristic whose root implies instability, when positive.