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Wray, A. A.

Publications and source records attributed to Wray, A. A..

24 records · Page 2

Big whorls carry little whorls

The aim of the research was to explore the space-time structure of homogeneous turbulence by computing and then interpreting the two-point spectra and correlations of the velocity and pressure fields. Many of these statistics are of considerable practical importance. In particular, it is of interest to compare the different time and length integral scales and microscales for Eulerian and Lagrangian qualities, and to compare the space and time spectra.

Hunt, J. C. R.

Simulating a Three-Dimensional Flow in Pipes

Numerical method simulates in unsteady, incompressible flow in axisymmetric pipe in three dimensions. Method relies on velocity-vector expansion technique in which each vector function in expansion set is divergence-free and satisfies boundary conditions for viscous flow.

Leonard, A.

Evolution of shock-induced pressure on a flat-face/flat-base body and afterbody flow separation

The time-dependent, compressible Reynolds-averaged, Navier-Stokes equations are applied to solve an axisymmetric supersonic flow around a flat-face/flat-base body with and without a sting support. Important transient phenomena, not yet well understood, are investigated, and the significance of the present solution to the phenomena is discussed. The phenomena, described in detail, are as follows: the transient formation of the bow and recompression shock waves; the evolution of a pressure buildup due to diffraction of the incident shock wave in the forebody and afterbody regions, including the luminosity accompanying the pressure buildup; the separation of the flow as influenced by pressure buildup; the location of the separation and the reattachment points; and the transient period of the shock-induced base flow. The important influence of the nonsteady (transient) and steady flow on the aerodynamic characteristics, radiative heat transfer, and, thus, on the survivability or safeguard problems for an aircraft fuselage, missile, or planetary entry probe at very high flight speeds is described.

Yoshikawa, K. K.

Steady and nonsteady supersonic turbulent afterbody flow

The effect of the specific heat ratio gamma of the incoming ideal gas on the flow properties, especially on pressure distributions along the base and sting surfaces and on reattachment distance, was investigated. The specific heat ratios considered were gamma = 1.2, 1.4, and 1.667. Also, effects of other major parameters, such as eddy-viscosity coefficient (or effective Reynolds number) and Mach number, on the afterbody pressure and reattachment distance were studied and are discussed. Evolution of shock induced flow and stabilization time were examined and are discussed for a transient problem. The important influence of the flow-field geometry, pressure distributions, and reattachment distance on the aerodynamics radiative heat transfer for an atmosphere entry probe in high speed flight are briefly described.

Yoshikawa, K. K.

Vectored injection into compressible laminar and turbulent boundary layers

A fundamental analysis of two-dimensional supersonic boundary layer flow, both laminar and turbulent, is presented for a wide range of normal and nonnormal mass-transfer velocities. The analysis is based on the numerical solution of the Navier-Stokes equations, and results are compared with available theoretical and experimental data. Certain cases of practical importance, for which results are not presently available, are referred to.

Degani, D.

Numerical simulation of transition to turbulence

The purpose of the present study is the numerical simulation of transition to turbulence in a boundary layer. Starting from a three-dimensional disturbance, the evolution of the Navier-Stokes solution until breakdown is followed. Qualitative comparison with available experimental observations is carried out.

Wray, A. A.