Published online by Cambridge University Press: 28 March 2006
Three results on the flow of an infinitely conducting and inviscid fluid are presented in this paper. The first result is that all steady flows with magnetic lines coincident with streamlines are reducible to flows without a magnetic field. The second result is on the establishment of a steady irrotational and current-free flow with coincident streamlines and magnetic lines. It throws some light on the controversy between Stewartson (1960) and Sears & Resler (1959) concerning the possibility of such a flow. The third result concerns the flow of a fluid through a circular cylinder of radius R into a point sink with strength m when the fluid carries a current of density j0 at infinity. It is shown that the condition of uniform flow at infinity is impossible to maintain if a dimensionless number (kR)2 involving the current density j0 exceeds the value (3·831)2, and that the current has the effect of concentrating the flow near the centre line and of producing ring eddies which become longer and longer as (kR)2 is increased.