Comment on “A numerical study of periodic disturbances on two-layer Couette flow” [Phys. Fluids 10, 3056 (1998)]

nt ysiThe flow of fluids with different viscosities, subjected an interfacial perturbation, can lead to fingering a migration. Both Refs. 2 and 3 refer to fingers in two dimensional studies, which would correspond to sheets three dimensions. Figure 19 of Ref. 3 shows a sequenc interface positions for initial amplitude 0.05, wave numb a5p/2, Reynolds number R15500, viscosity ratiom50.5, undisturbed interface height l 150.372, and interfacial ten sion parameterT50.01, at times 0, 5, 10, 15, and 20 carried out on a 256 3256 mesh. A region of high curvatur forms, followed by pinching into a series of horizontal drop However, the drops are at the scale of the numerical mes spatial convergence test is reported here, showing that w refined mesh, the drops are replaced by an elongated fin