Resuspension threshold of a granular bed by localized heating

TL;DR

This study experimentally examines how localized heating can induce fluidization and resuspension of granular beds, revealing threshold conditions based on temperature, bed thickness, and buoyancy effects, relevant for industrial and environmental processes.

Contribution

It introduces a new experimental approach to determine the resuspension threshold of granular beds caused by localized heating, highlighting the roles of thermal conductivity and buoyancy parameters.

Findings

Resuspension occurs beyond a specific threshold temperature.

Threshold depends on bed thickness and buoyancy number.

Fluidization results in particle-laden plumes transport.

Abstract

The resuspension and dispersion of particles occur in industrial fluid dynamic processes as well as environmental and geophysical situations. In this paper, we experimentally investigate the ability to fluidize a granular bed with a vertical gradient of temperature. Using laboratory experiments with a localized heat source, we observe a large entrainment of particles into the fluid volume beyond a threshold temperature. The buoyancy-driven fluidized bed then leads to the transport of solid particles through the generation of particle-laden plumes. We show that the destabilization process is driven by the thermal conductivity inside the granular bed and demonstrate that the threshold temperature depends on the thickness of the granular bed and the buoyancy number, i.e., the ratio of the stabilizing density contrast to the destabilizing thermal density contrast.