Abstract
We consider the Rayleigh-Taylor instability in exponential density profiles and derive two approximate expressions for the growth rate that are explicit and involve only the Atwood number A and the wave number k. Our results agree with the exact growth rate within 612 %. We also point out that a recently published expression deviates from the exact growth rate for practically all values of A and k [M. H. Emery, J. P. Dahlburg, and J. H. Gardner, Phys. Fluids 31, 1007 (1988)]. DOI: http://dx.doi.org/10.1103/PhysRevA.40.4801 © 1989 The American Physical Society