Erratum: ‘‘Linear stability of plane Poiseuille flow of two superposed fluids’’ [Phys. Fluids 31, 3225 (1988)]

(Received 20 January 1989; accepted 21 January 1989) The above Brief Communication by Nanbu, Igarashi, and Watanabe is concerned with the errors that are intro­duced if a radial flow with spherical symmetry is calculated as a three-dimensional flow in a cone with a large apex angle, but with a cell structure only in the radial direction. The purpose of this Comment is to point out that the problem can be completely eliminated by procedures that date back