Authors: Chen Shi (UCLA), Nikos Sioulas (UCLA), Zesen Huang (UCLA), Marco Velli (UCLA), Anna Tenerani (UT Austin)

We carry out 3D magnetohydrodynamic (MHD) simulations of weak, decaying turbulence. Expanding box model is implemented so that spherical expansion of the solar wind is accounted. The turbulence is anisotropic along the three axes. We show that negative residual energy is produced whenever nonlinear interaction exists regardless of the normalized cross helicity \sigma_c, and the spherical expansion facilitates the process. The residual energy is mainly distributed in the perpendicular direction with E_r \propto k_\perp^{-2}. The magnetic field develops a second-order structure function S2(b) \propto l_\perp^{1/2}. The velocity’s second-order structure function S2(v) is systematically shallower than S2(b), consistent with in-situ observations of the solar wind. We show that higher-order statistics of the turbulence, proxy of intermittency, depends strongly on the initial \sigma_c as well as whether the expansion effect is present. In general, the fluctuation is more multi-fractal when expansion effect exists and is more multi-fractal when the initial fluctuation is imbalanced than the balanced case.