Doctoral Dissertations

Winter 1995

Dissertation

Engineering

Degree Name

Doctor of Philosophy

Simultaneous quantitative measurements are made of both the temperature and velocity fields for two-dimensional transient natural convection in an inclined rectangular enclosure. The fluid in the enclosure is initially stationary and isothermal. The transient boundary conditions are initiated by instantaneously heating and cooling two opposing walls. All other walls are insulated and nonconducting. The evolution of the flow to steady state is determined for a Prandtl number of 6.38, a Rayleigh number of 1.5 $\times$ 10$\sp5$, and an aspect ratio of 1.0, at angles of inclination of $\pi$/4, $\pi$/2, and 3$\pi$/4. The temperature is measured using calibrated multichannel electronic interferometry, and the velocity is measured using digital particle image velocimetry. This allows accurate measurement of the temperature and velocity fields throughout the enclosure and visualization of the boundary layers, intrusion layers, and recirculation zones. The angle of inclination is shown to have a significant effect on the flow and heat transfer. However, the expected transient oscillations are not evident. This is probably due to differences in the boundary conditions at startup between the current experiments and the numerical simulations.