Accession Number : AD0824134

Title :   ON THE USE OF AVERAGE VISCOSITY IN THERMAL INSTABILITY PROBLEMS.

Descriptive Note : Research memo.,

Corporate Author : GRUMMAN AIRCRAFT ENGINEERING CORP BETHPAGE NY RESEARCH DEPT

Personal Author(s) : McIlroy, W. ; Keen, K.

Report Date : NOV 1967

Pagination or Media Count : 14

Abstract : In a study of the interaction of a submerged disturbance with an unstable fluid layer it was necessary to simulate this condition in the laboratory. This was achieved by heating a fluid from below to produce a density inversion that is inherently unstable. The temperature profiles and layer thicknesses required for this simulation dictated use of a fluid with a temperature sensitive viscosity. Most of the analytical work related to this problem had considered only constant fluid properties or the use of average values when these properties were considered temperature-dependent. To determine where use of the average value is justified, a linear variation of viscosity across the fluid layer was included in the governing equations, and its effect was examined. In particular, the effect upon the critical Rayleigh number and the error introduced by using average values were evaluated for a variety of boundary conditions.

Descriptors :   *THERMAL STABILITY), (*FLUID FLOW, HEAT FLUX, DENSITY, TEMPERATURE, THICKNESS, VISCOSITY, BOUNDARY LAYER, EQUATIONS OF MOTION, DIFFERENTIAL EQUATIONS, MATRICES(MATHEMATICS).

Subject Categories : Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE