Sound waves in fluidized bed using CFD–DEM simulations--颗粒学报PARTICUOLOGY

Khawaja, H. A. (2018). Sound waves in fluidized bed using CFD–DEM simulations. Particuology, 38, 126-133. https://doi.org/10.1016/j.partic.2017.07.002

Sound waves in fluidized bed using CFD–DEM simulations

Hassan Abbas Khawaja ^*

Process and Gas Group, Department of Engineering & Safety, UiT-The Arctic University of Norway, 9037 Langnes, Tromsø, Norway

10.1016/j.partic.2017.07.002

Volume 38, June 2018, Pages 126-133

Received 24 February 2017, Revised 28 June 2017, Accepted 4 July 2017, Available online 16 October 2017, Version of Record 2 April 2018.

E-mail: hassan.a.khawaja@uit.no; hassan.abbas.khawaja@gmail.com

Highlights

• CFD–DEM simulations were used to study sound waves in a two-phase medium.

• Appropriate boundary conditions were applied at conditions very close to minimum fluidization.

• CFD–DEM results were in agreement with previous theoretical studies.

• New correlations were derived for the speed and damping in sound waves in two-phase medium.

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.

Graphical abstract

Keywords

Fluidized bed; Sound waves; Speed of sound; Damping time; CFD–DEM simulations

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