Fluid Simulations of the Spectral Break Observed in Magnetic Field Power Spectra at the Proton Gyroscale

Solar wind observations show evidence of a spectral break in the power spectrum of the magnetic field close to the wave number corresponding to the proton gyroscale. The nature of this spectral break is not well understood and it is often speculated as to which physical mechanism plays a dominant role in its origin. We will present 3D numerical simulations with classical fluid models and with Landau fluid models (which contain kinetic effects). As a basic model we will use the isotropic 2-fluid model (compressible Hall-MHD) and explore how the spectral break is modified by the inclusion of anisotropic pressure fluctuations (CGL model), inclusion of proton and electron Landau damping (large-scale Landau fluid model) and inclusion of finite Larmor radius (FLR) corrections (FLR-Landau fluid model).