Experimental studies in buoyancy-driven exchange flows and turbulent jet

Abstract

Buoyancy drives many flows in nature as well as in industrial processes. It drives the climate - it plays an important role in the vertical transport of heat and water vapour. Buoyancy also acts as a restoring force in the interaction between the ocean and the atmosphere. At a much smaller scale, buoyancy is used by sea creatures to maintain their depth. Ships and submarines use buoyancy for desirable effects. The present study focuses primarily on the buoyancy-induced flows that are relevant in natural ventilation and fire-fighting applications. Energy can be naturally extracted from buoyancy from the motion it sets due to the difference in weights of two interacting fluids. We see that, for example, when we open a window and a gush of air enters the room. It was reported in October 2015 that the world has started using more energy in cooling than heating 1. The energy required to cool (and heat) buildings comes at a cost to the environment. The California Energy Commission is enforcing laws that require all buildings to be zero net energy buildings by the year 2030 2. Renewable energy does help, but the process needs to be supplemented with more efficient designs for buildings. Most buildings are designed with a window approximately at a central level of the room since the fluid exchange happens at this level. As the room gets heated due to occupants and various devices that emit heat, the hot air rises to the top of the room. Ideally, one would want a room where the cold air enters at the bottom level displacing the hot air from the top.