The steady motion of an infinitely long solid cylinder parallel to its length in a conducting fluid in the presence of a uniform magnetic field is discussed. Due to Alfvén waves originating at the cylinder we find two opposite ‘wakes’ parallel to the applied magnetic field.
A formula which relates the total drag on the cylinder to the electric potential difference δΦ between the two undisturbed regions outside these two wakes is derived
$D|\;|\delta \Phi| = 2\surd {\rho}v \sigma$
where ρν is the viscosity and σ is the conductivity of the fluid.
The reduction to a classical boundary-value problem is made for the case of an insulating cylinder.
Exact solutions are obtained for the case of a perfectly conducting or an insulating flat strip of semi-infinite width. These give a clear picture of the field, especially in the transition region near the edge of the strip.
The case of a strip of finite width is also discussed with special reference to the viscous and the magnetic drags, Df and Dm. We find that Df + ½Dm, on a perfectly conducting strip, is equal to the viscous drag on an insulating strip for which Dm is zero. Precise values of these drags are given.