Nearly incompressible turbulence for different 2D and slab energy ratios

Abstract

Zank et al 2017 [1] developed equations describing the transport of 2D and slab turbulence based on nearly incompressible magnetohydrodynamic (NI MHD) theory. Zank et al [1] discussed preliminary solutions of the model equations, and Adhikari et al [2] provided a detailed analysis of the model equations. Their analyses of the 2D and slab turbulence transport model equations were based on the ratio of the inner boundary values of the 2D and slab energies being of the order 80:20. Here, we investigate the effect of choosing the 2D and slab energy ratios to be 80:20, 70:30, 60:40, and 55:45 for the boundary energy values, and solve the 2D and slab turbulence transport model equations. We compare our theoretical results with observations made by Voyager 2 and Ulysses. We find that the 2D and slab turbulent quantities such as the energy in forward and backward propagating modes, the fluctuating kinetic and magnetic energy, for example, are different for different boundary values, but show similar trends with increasing heliocentric distance. In addition, we also investigate the model equations by including a shear source of turbulence in the slab turbulence transport equations. This was not considered by [1] and [2]. We find that the slab turbulent quantities behave more reasonably in the presence of both shear and pickup ion sources of turbulence.