Turbulent Surface Jet in Channel of Limited Depth

Abstract

The synoptic behavior of a two‐dimensional turbulent surface jet is experimentally investigated. Single‐point hot‐film data were obtained for mean and root‐mean‐square velocities in the developing jet to a distance of 240 characteristic lengths downstream of the origin. The growth rates of the length and velocity scales are found to resemble more closely those observed in wall jets than those in free jets. The effects of jet confinement are to retard the ability of the jet to entrain fluid, to decrease the growth rate of the length scale, and to increase the decay rate of the velocity scale. Mean velocity‐profile similarity is still observed when the data is nondimensionalized with the reduced scales. Jet momentum will appear to have been lost due to momentum exchange with the return flow. An approximate analysis provides a means to estimate the momentum loss due to limited‐depth and is shown to correlate well with scale development in several jet configurations for these and prior experiments.