Stably Stratified Flows — Lesson 1

This lesson covers the concept of stably stratified flows, which are crucial for atmospheric applications. The lesson begins with an explanation of the configuration of stably stratified turbulence, where the dense fluid sits at the bottom due to gravity and the light fluid is above. The lesson then delves into the equations for stably stratified flows, explaining the role of gravity and density in these equations. The lesson also discusses the impact of these forces at different scales and how they affect the scaling, spectrum, or flux. The lesson concludes with an exploration of the three types of stably stratified flows: moderately stratified flow, weak stratification, and strong stratification.

Video Highlights

00:25 - Introduction to stably stratified flows and its importance in atmospheric applications
02:26 - Discussion on the impact of density acting at all scales
05:29 - Explanation of the equation for density fluctuation
09:34 - Explanation of the energy equation for stably stratified flows
20:52 - Discussion on the regimes of stably stratified flows and the Bolgiano-Obukhov theory for moderate stratification
26:15 - Explanation of the derivation of the spectrum for stably stratified flows

Key Takeaways

- Stably stratified flows are important for atmospheric applications, with the dense fluid sitting at the bottom due to gravity and the light fluid above.
- The forces of gravity and density play a significant role in the equations for stably stratified flows.
- These forces impact different scales and can affect the scaling, spectrum, or flux.
- There are three types of stably stratified flows: moderately stratified flow, weak stratification, and strong stratification.
- The flux of kinetic energy decreases with wave number in stably stratified flows due to the sapping of kinetic energy at every scale.