Turbulence Models in Magnetohydrodynamics — Lesson 3

This lesson covers the complex topic of energy turbulence models for Magnetohydrodynamics (MHD). It delves into the theories and models proposed by various researchers, including the Kolmogorov model, the Kraichnan Iroshnikov’s model, and the Goldreich Sridhar model. The lesson also discusses the concept of energy transfers, fluxes, and the role of Alfven waves in MHD turbulence. It further explores the unsolved problems and divergences in these models, emphasizing the lack of a universally accepted model due to the large number of variables involved. The lesson concludes with a discussion on the indirect predictions and the need for further research in this field.

Video Highlights

00:24 - Introduction to energy turbulence models for MHD and the Kolmogorov model
01:57 - Explanation of the Kraichnan Iroshnikov’s model
08:47 - Explanation of the Marsch model and the concept of critical balance
12:53 - Discussion on the Goldreich Sridhar model and the concept of anisotropy
26:26 - Explanation of the structure function in the context of MHD turbulence
32:29 - Presentation of the results from numerical simulations on MHD turbulence

Key Takeaways

- Energy turbulence models for MHD are complex and involve a variety of theories and models.
- The Kolmogorov model is effective for hydro as long as the energy is forced at large scales.
- The Kraichnan Iroshnikov’s model, despite being misinterpreted, plays a significant role in understanding MHD turbulence.
- Alfven waves are key to modeling MHD turbulence.
- There is no universally accepted model due to the large number of variables involved.
- Further research and testing are needed to validate these models and theories.