# Cross-helically forced and decaying hydromagnetic turbulence

## TL;DR

This paper investigates how strong cross helicity influences the evolution of kinetic and magnetic energy spectra in magnetohydrodynamic turbulence, revealing inverse energy transfer and exponential decay phenomena.

## Contribution

It provides new insights into the spectral evolution of MHD turbulence under strong cross helicity, including inverse transfer and decay suppression mechanisms.

## Key findings

- Weak inverse transfer of kinetic energy in forced turbulence.
- Exponential decay of energy over a range of wavenumbers.
- Dominance of kinetic over magnetic energy at small scales.

## Abstract

We study the evolution of kinetic and magnetic energy spectra in magnetohydrodynamic flows in the presence of strong cross helicity. For forced turbulence, we find weak inverse transfer of kinetic energy toward the smallest wavenumber. This is plausibly explained by the finiteness of scale separation between the injection wavenumber and the smallest wavenumber of the domain, which here is a factor of 15. In the decaying case, there is a slight increase at the smallest wavenumber, which is probably explained by the dominance of kinetic energy over magnetic energy at the smallest wavenumbers. Within a range of wavenumbers covering almost an order of magnitude the decay is purely exponential, which is argued to be a consequence of a suppression of nonlinearity due to the presence of strong cross helicity.