Fluid Energy Cascade Rate and Kinetic Damping: New Insight from 3D Landau-fluid Simulations

Using an exact law for incompressible Hall magnetohydrodynamics (HMHD) turbulence, the energy cascade rate is computed from three-dimensional HMHD-CGL (biadiabatic ions and isothermal electrons) and Landau-fluid numerical simulations that feature different intensities of Landau damping over a broad range of wavenumbers, typically 0.05 less than or similar to k(perpendicular to) d (i) less than or similar to 100. Using three sets of cross-scale simulations where turbulence is initiated at large, medium, and small scales, the ability of the fluid energy cascade to sense the kinetic Landau damping at different scales is tested. The cascade rate estimated from the exact law and the dissipation calculated directly from the simulation are shown to reflect the role of Landau damping in dissipating energy at all scales, with an emphasis on the kinetic ones. This result provides new prospects on using exact laws for simplified fluid models to analyze dissipation in kinetic simulations and spacecraft observations, and new insights into theoretical description of collisionless magnetized plasmas.

Automated summary

This study calculates the energy cascade rate in incompressible Hall magnetohydrodynamics turbulence using an exact law and shows the role of Landau damping in dissipating energy at all scales. It provides new prospects for analyzing dissipation in kinetic simulations and spacecraft observations, as well as new insights into theoretical description of collisionless magnetized plasmas.