Turbulent Entrainment in Jets: The role of Kinetic Energy

Abstract

In free shear flows the flow field can be divided into two distinct regions that find themselves separated by a thin contorted front entitled turbulent/nonturbulent interface. In the outer region the flow is largely irrotational whereas in the inner region the flow is turbulent. Turbulent entrainment is the process through which fluid parcels from the outer region acquire vorticity, thus becoming turbulent. Recently, the classical assumption, where large scale “engulfing” motions are the main responsible for the jet growth [?], has been questioned e.g. Mathew ' Basu [?] and Westerweel et. al. [?]. Instead, these works provided ample support to the original model of Corrsin ' Kistler [?], where the entrainment is mainly governed by small scale eddy motions (“nibbling”).