a1 Sch. Natural Sciences, University of California Merced, 5200 N. Lake Rd, Merced, CA 95343, USA
a2 Dept. Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
We present the results of a combined theoretical and experimental study of the stability of a uniformly stratified fluid bounded by a sidewall moving vertically with constant velocity. This arrangement is perhaps the simplest in which boundary effects can drive instability and, potentially, layering in a stratified fluid. Our investigations reveal that for a given stratification and diffusivity of the stratifying agent, the sidewall boundary-layer flow becomes linearly unstable when the wall velocity exceeds a critical value. The onset of instability is clearly observed in the experiments, and there is good quantitative agreement with some predictions of the linear stability analysis.
(Received December 24 2007)
(Revised April 16 2008)