Formation and displacement of bubbles in a packed bed

TL;DR

This study visualizes how bubbles form and move within a packed bed submerged in water, revealing two flow regimes influenced by air flow rate and their effects on particle dynamics.

Contribution

It provides detailed visualization and analysis of bubble formation and displacement in a packed bed, highlighting the transition between percolation and accumulation regimes.

Findings

Low flow rates cause air to percolate through interstitial spaces.

High flow rates lead to air accumulation and particle circulation.

Bubbles can displace particles and alter flow patterns.

Abstract

The fluid dynamics video show a gas stream which is injected into a packed bed immersed in water and fluid dynamcis video present the dynamics involved. The refractive index of the water an the packed bed are quite similar and the edges of the spherical particles can be seen. Two distinctive regimens can be observed. The first one, for low air flow rates, which is characterized by the percolation of the air thought the interstitial space among particles. And the second one, for high air flow rates, which is characterized by the accumulation of air inside the packed bed without percolation, it can be observed that the bubble pull apart the particles apart. Furthermore, for the first case the position of the particles remains constant while for the second one a circulation of particles is induced by the bubbles flow.