Granular pressure in a liquid‐fluidized bed as revealed by diffusing wave spectroscopy

Abstract

in Wiley Online Library (wileyonlinelibrary.com).The granular pressure and granular temperature underpin various models of granular flows while they are playing an increasing role in modeling of other phenomena in granular systems such as heat transfer, segregation, erosion, attrition, and aggregation. The development and validation of these theories demand experimental determination of these two quantities. Diffusing wave spectroscopy (DWS) is now an accepted technique for measurement of granular temperature in dense granular systems. Using granular temperature data obtained from DWS with the kinetic theory of granular flow, we have derived the granular pressure data for a liquid-fluidized bed. The determined variation of the mean bed granular pressure with mean bed solid volume fraction compares favorably with previously published experimental data and theoretical models of others. Where discrepancies do occur, they may be attributed to differences in particle inertia, suggesting further work on granular pressure models is required. Finally, we report the variation of the granular pressure with height above the distributor for several mean solids volume fractions.

Particle dynamics in sheared particulate suspensions

“…Measurements of granular temperature in dense granular systems and suspensions have traditionally been made using diffusing wave spectroscopy, particle imaging velocimetry (PIV), and laser Doppler velocimetry (LDV) techniques. The main limitations of the PIV and LDV methods are that both techniques use seeded particles and require the medium to be optically transparent.…”

Determining key variables of the kinetic theory of granular flow using DWS

“…This makes liquid FBs particularly suitable for the task at hand [19]. Despite this, as far as we are aware, there are only three such studies in which experimental data for liquid FBs is used to determine granular pressure and viscosity: our recent paper on granular pressure [20], Zenit et al [21] also for granular pressure, and Gidaspow & Huilin [22] for granular viscosity.…”