MHD-Drift Equations: from Langmuir circulations to MHD-dynamo?
  We have derived the closed system of averaged MHD-equations for general oscillating flows, which are purely oscillating in the main approximation. We have used the mathematical approach which combines the two-timing method and the notion of the distinguished limit. Properties of the commutators are used to simplify calculations. The direct connection with a vortex dynamo (or the Langmuir circulations) has been demonstrated and a conjecture on the MHD-dynamo has been formulated. 
Vladimir A. Vladimirov
physics.flu-dyn astro-ph.EP math-ph math.MP nlin.PS