Yaglom law in the expanding solar wind

摘要: We study the Yaglom law, which relates mixed third order structure function to average dissipation rate of turbulence, in a uniformly expanding solar wind by using two scales expansion model magnetohydrodynamic (MHD) turbulence. show that due new terms appear law. The first term is related decay turbulent energy nonlinear interactions, whereas second non-zero cross-correlation Els\"asser fields. Using magnetic field and plasma data from WIND Helios 2 spacecrafts, we at lower frequencies inertial range MHD turbulence become comparable Yaglom's moment, therefore they cannot be neglected evaluation cascade wind.