SURFACE MANIFESTATIONS OF TURBULENT-FLOW

The surface of a turbulent, open-channel flow is often characterized b y smooth areas of upwelling, each surrounded by a zone of downwelling marked by short steep waves. The dynamics of short waves on such a dow nwelling region are investigated and some laboratory experiments are p roposed. Assuming that the horizontal strain rate Omega is locally con stant, a simple expression is derived for the amplitude alpha of the s hort capillary-gravity waves, and hence also for the spectrum of the s urface slopes.