Sound waves in fluidized bed using CFD–DEM simulations

Abstract

The speed of sound waves in a fluidized bed is investigated using CFD–DEM numerical simulations. Appropriate initial and boundary conditions are applied to reproduce bed phenomena. The effect of varying the height of the bed is also studied. The results of the simulations matched those from the literature. The pressure and particle velocity profiles obtained feature oscillatory behavior to which functions (based on a damped standing wave) were fitted, enabling an explicit dependence on time and space variables to be established. These fitted functions were substituted into the linearized governing equations for the two-phase flow. These solutions enabled a new relationship to be derived for the speed of sound and damping in the system. The conclusion drawn is that the damping in the system is governed by the effective bulk viscosity of the solid phase, which arises from the particle viscosity.