Energy Spectrum and Flux of Buoyancy-Driven Turbulence

Gravity or buoyancy plays an important role in atmospheric and geophysical flows. The flow is destabilized when heavier or colder fluid is on top of a lighter or hotter fluid, often seen in thermal convection (Fig 1(a)). Convection plays an important role in interiors of many planets and stars, and it is one of the mechanisms for the generation of a magnetic field. Conversely, the flow is stabilized when a lighter fluid sits on top of a heavier fluid, for example, in Earth’s atmosphere (Fig 1(b)). The latter configuration, called stably stratified, can be made turbulent by an additional stirring of the fluid. Kumar et al. [1], and Kumar and Verma [2] examined this problem, and provided a comprehensive theory for the energy spectrum and flux of such flows in a turbulent limit.