MHD turbulence in the solar wind: highlights on the effects of expansion

International audienceProperties of solar wind fluctuations are often interpreted as those of a homogenous turbulent plasma, at MHD or ion scales. However solar wind turbulence is not homogenous, being embedded in a spherically expanding flow of approximately constant speed. We briefly review some of the recent results on MHD turbulence obtained with the Expanding Box Model (EBM), which reveal the influence of expansion on the spectral anisotropy, the component anisotropy, and the z /z- imbalance. We then focus on structure functions, computed in frames attached to the local or global mean field, and show that most of the observed features are well reproduced in our EBM simulations. We finally comment on the role of expansion in determining the injection scale of solar wind turbulence and its anisotropy