The glancing interaction between an oblique shock wave and a turbulent boundary layer has been studied experimentally using a variable-incidence wedge mounted from the side wall of a supersonic wind tunnel. The Mach number was 2·3 and the Reynolds number 5 × 104, based on the 99·5 % thickness of the boundary layer just upstream of the interaction region. The study includes oil flow pictures, vapour and smoke-screen photographs, wall-pressure distributions and local heat-transfer measurements. The results suggest that the complicated interaction region involves two viscous layers: an induced layer formed from fluid initially in the boundary layer growing along the wedge surface near the root, and the thick turbulent layer on the tunnel side wall. The mutual interference between these layers is described, separation is defined and a discussion of incipient separation is included.

This paper is concerned with fluid flows through membranous elastic tubes. The tubes are assumed to be either untethered (except at the ends), or to be tethered by axial forces that prevent all axial motion of the tube.

First we verify, for axisymmetric deformations that vary slowly in the axial direction, that the elastic balance of the tube can be expressed in terms of a ‘tube law’. In the case of the tethered tubes, the tube law takes the widely used form of a pressure/area relation for both steady and unsteady deformations. However, for untethered tubes, the tube law will generally be time-dependent if the deformations are unsteady. Conditions are then derived between the up- and downstream flows of a turbulent elastic jump. Although it is necessary for the elastic balance to be described by a tube law far up- and far downstream of the jump, we do not assume that the tube law is valid inside the jump. The conditions we derive are believed to hold for both collapsed and expanded tubes.

The theory has applications in describing fluid flows within, for example, the airways, blood vessels and the urethra.

The purpose of this paper is to present numerical solutions for two-dimensional time-dependent flow about rectangles in infinite domains. The numerical method utilizes third-order upwind differencing for convection and a Leith type of temporal differencing. An attempted use of a lower-order scheme and its inadequacies are also described. The Reynolds-number regime investigated is from 100 to 2800. Other parameters that are varied are upstream velocity profile, angle of attack, and rectangle dimensions. The initiation and subsequent development of the vortex-shedding phenomenon is investigated. Passive marker particles provide an exceptional visualization of the evolution of the vortices both during and after they are shed. The properties of these vortices are found to be strongly dependent on Reynolds number, as are lift, drag, and Strouhal number. Computed Strouhal numbers compare well with those obtained from a wind-tunnel test for Reynolds numbers below 1000.

The Ffowcs Williams-Hawkings formulation of the sources of the acoustic analogy is examined by reference to two compressible inviscid flows whose density and velocity fields are known exactly. The purpose of this exercise is to generate some feel for the importance of the various source terms in determining the sound of moving surfaces with shocks, and to help quantify the errors involved in approximating those sources. Practical applications of the theory involve flows that cannot be known exactly and the errors of approximation cannot be checked directly. Progress must start with simple cases, and these model problems represent a first move. The flows considered are the one-dimensional flow caused by a plane boundary impulsively accelerated into a fluid, and the two-dimensional flow due to a wedge moving supersonically and supporting a plane attached shock.

For each of these flows, a system of analogous acoustic sources is developed, the fields of which, when superposed, produce a density field (an acoustic field) identical with that of the original flow. The acoustic fields generated by the component source terms are calculated and compared. This suggests that the volume quadrupoles of potential flow play only a minor role as sound generators. When properly viewed the field is generated entirely on the bounding surfaces of the flow. A general argument shows that volume quadrupoles in steady rectilinear motion only influence the sound field through propagation effects.