Authors: V. David (Space Science Center And Department Of Physics And Astronomy, University Of New Hampshire, Durham, NH 03824), B .D. G. Chandran (Space Science Center And Department Of Physics And Astronomy, University Of New Hampshire, Durham, NH 03824), R. Meyrand (Space Science Center And Department Of Physics And Astronomy, University Of New Hampshire, Durham, NH 03824), J. Squire ( Physics Department, University Of Otago, Dunedin 9010, New Zealand), E. L. Yerger (Space Science Center And Department Of Physics And Astronomy, University Of New Hampshire, Durham, NH 03824)

We derive a set of simplified equations that can be used for numerical studies of RMHD turbulence within a small patch of the radially expanding solar wind. We allow the box to be either stationary in the Sun’s frame or to be moving at an arbitrary velocity along the background radial magnetic field lines. To aid in the design and optimization of DNS, we express the equations in terms of scalar potentials and Clebsch coordinates. The equations we derive will be particularly useful for conducting DNS of reflection-driven MHD turbulence in the solar wind, and may also be useful for studying turbulence within other astrophysical outflows.