On buoyancy transfer across an entrainment interface

A striking feature observed during the turbulent entrainment across a density interface at moderately-large Richardson numbers is the presence of an intermediate layer sandwiched between the well-mixed and interfacial layers. In this note, a possible mechanism for its origin, and its role in buoyancy transfer during the entrainment is discussed. Estimates are made for the thickness of the intermediate layer and are compared with experimental results.Also Environmental Engineering Science, California Institute of Technology, Pasadena, CA 91125, U.S.A.