Turbulent momentum transport and kinetic energy production in plane-channel flows

Based on a momentum balance analysis, this paper basically presents and discusses experimental results from fully developed turbulent plane-channel flows utilizing hot-wire anemometer. The paper stresses the fact that in experimental investigations of two-dimensional shear flows it is difficult to obtain, with reasonable accuracy, all turbulent quantities of interest to fluid mechanics researchers. This makes it necessary to measure some relevant turbulent flow properties as a basis to drive others by utilizing theoretically derived relationships obtained from the mean momentum equation. It is demonstrated that both the turbulent Reynolds shear stress -ρu1′u2′¯ and the kinetic energy production -ρu1′u2′¯(dU¯/dy) for two-dimensional fully developed turbulent flows can be predicted in this way through detailed mean velocity and mean pressure gradient measurements. In addition, some flow similarities and differences among channel, pipe and boundary layer flows are discussed, revealing effects of flow geometry and Reynolds number on the mean flow scaling.