The study of flow induced phenomena at the interface between a solid body and a fluid in contact with it is essential to the understanding of such vital engineering problems as drag, flow noise and other energy dissipation characteristics of turbulent flow. At present, investigations have been made of flow properties near a solid boundary and the results extrapolated to the boundary itself by means of energy and momentum conservation principles. The results of these experiments tend to support the theory; however, the data is sparse and many assumptions and secondary mathematical relations must be used before this can be achieved. In this study shear stress was measured at the wall itself using flush-mounted hot-film anemometers. The purpose was to test two models of the structure of the viscous sublayer. The test apparatus consisted of a pipe four inches in diameter and forty feet long connected to a water reservoir in a closed loop design. The test section was located near the end of the pipe to assure fully developed flow conditions. Fluctuating wall shear stress was measured to determine a model of the viscous sublayer.

The results of an experimental investigation of the effects of a flexible boundary on pressure drop in turbulent flow in a pipe are reported. A test section was made by casting a highly compliant, elastic gel between two concentric pipes. The inner pipe was then removed leaving a flexible boundary for flow studies. Fluid was caused to flow through the test section and pressure drop measurements were recorded at Reynolds numbers ranging from 1800 to 15,200. The pressure drop across the flexible boundary was found to be greater than that encountered in a similar section with a solid boundary. Below Re 13,500, this increase can be explained either in terms of effective wall roughness or by an effect of the flexible boundary on turbulence. Above Re 13,500, the data indicate a pressure drop increase due to the effects of the flexible boundary. (Author).