Helical Turbulence — Lesson 1

This lesson covers the concept of Helical Turbulence, focusing on kinetic helicity and its control. It revisits the conservation laws, kinetic helicity transfer formula, mode to mode transfer, and the phenomenology of helical turbulence. The lesson also delves into the numerical results of these concepts. It explains the definition of total helicity and its relation to viscosity. The lesson further discusses the Fourier space and the derivation of the kinetic helicity equation. It also covers the concept of kinetic energy and helicity flux, and how they are affected by the presence of helicity. The lesson concludes with a discussion on the spectrum for helicity and the energy spectrum.

Video Highlights

00:29 - Discussion on conservation laws, kinetic helicity transfer formula, and mode to mode transfer
03:08 - Discussion on kinetic helicity equation and its implications
11:26 - Discussion on phenomenology of helical turbulence
16:16 - Discussion on kinetic energy spectrum and helicity
21:58 - Explanation of kinetic helicity spectrum and its relation to kinetic energy flux
28:28 - Discussion on helicity spectrum and helicity flux

Key Takeaways

- Total helicity is defined as u dot omega, and it is conserved in 3D when viscosity equals 0.
- The kinetic helicity equation is derived from the Fourier space.
- The kinetic energy and helicity flux are not significantly altered by the presence of helicity.
- The kinetic energy spectrum remains the same irrespective of the presence of helicity.
- The helicity spectrum and kinetic energy flux can be derived using dimensional analysis.