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Updated: Jun 3, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Venting dynamics of an immersed granular layer.
Germán Varas1, Valérie Vidal, Jean-Christophe Géminard
1Laboratoire de Physique, Université de Lyon, Ecole Normale Supérieure-CNRS, Lyon, France.
Summary
Gentle air injection into granular beds creates localized bubble plumes at the surface. A diffusion-like process, dependent on system parameters, governs the size of this bubble emission region.
Area of Science:
- Fluid dynamics
- Granular materials science
- Physics of multiphase flow
Background:
- Understanding gas flow through porous media is crucial in various industrial and natural processes.
- The behavior of gas injected into immersed granular beds is complex and not fully characterized.
- Localized gas venting can lead to unpredictable surface phenomena.
Purpose of the Study:
- To investigate the mechanism of bubble formation and emission from an immersed granular bed upon local air injection.
- To visualize and quantify the spatial distribution of gas venting at the free surface.
- To develop a theoretical model explaining the size of the bubble emission region.
Main Methods:
- Local air injection at the base of an immersed granular bed.
- Two-dimensional experiments for direct visualization of gas pathways.
- Theoretical modeling based on a diffusion-like process.
Main Results:
- Observed localized gas venting resulting in bubble emission in a specific surface region.
- Direct visualization confirmed the formation of distinct gas pathways through the granular material.
- A theoretical model successfully accounted for the size of the surface emission region using a diffusion coefficient.
Conclusions:
- The size of the localized bubble emission region at the free surface of an immersed granular bed is governed by a diffusion-like process.
- The derived diffusion coefficient is a function of the system's parameters, offering predictive capabilities.
- This study provides insights into gas-particle interactions and surface phenomena in granular systems.
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