Instabilities of buoyancy driven flows in a confined environment

Buoyancy driven flows are important in many geophysical and environmental applications: from natural ventilation in buildings to the evolution of cloud particles after a volcanic eruption or an explosion. Much work has been done on these flows in both turbulent and laminar flow regimes. However, the impact of lateral confinement on the flow has not received as much attention. One of the distinctive features is the development of an instability due to lateral shear. This effect can have important consequences for the large scale dynamics as well as the small scale mixing and dispersion properties of these flows when carrying particles or other tracers.

In this project, we will explore experimentally and theoretically the origin of the instability for various fundamental buoyancy-driven flows such as fountains and thermals. New experimental techniques, based on novel experimental design and imaging techniques, recently developed in our laboratory have allowed to probe further into the complex dynamics of these flows. The goal of this project is to study the phenomenology of the flow in order to determine the source of the instability. We will also analyse how the instability affects mixing and dispersion of active or passive tracers.

The project is suitable for an enthusiastic and creative candidate who has some experience in laboratory experimentation and good knowledge in fluid mechanics. Some knowledge in imaging analysis technique is desired but not necessary.