Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Interferometric and finite difference numerical techniques were employed to study free and mixed convection in open rectangular, semi-cylindrical, and V-shaped isothermal cavities.;An interlocking/overlapping technique was introduced to solve the semi-cylindrical cavity numerical problem.;A Mach-Zehnder interferometer was employed for the experimental free convection, and when integrated with an open circuit low-speed wind tunnel, the interferometer was utilized to study mixed convection.;The parameters within the ranges of Rayleigh number, 10{dollar}\sp3 \leq{dollar} Ra {dollar}\leq{dollar} 5 {dollar}\times{dollar} 10{dollar}\sp5{dollar}, the height to width aspect ratio, 0 {dollar}\leq{dollar} H/W {dollar}\leq{dollar} 1, the angle of inclination, 0{dollar}\sp\circ\leq\alpha\leq60\sp\circ{dollar}, Reynolds number of 380 and 400 and Prandtl number of 0.71 were considered.;For isothermal rectangular cavity there was no distinct conduction regime similar to that observed in cavity heated from the base only, where critical Rayleigh number, Ra{dollar}\sb{lcub}\rm c{rcub}\simeq\ 10\sp3{dollar}. Free convection in isothermal cavity occurred at lower Rayleigh number (Ra {dollar}<{dollar} 10{dollar}\sp3{dollar}). As Ra increased further, air was entrained into the cavity from both sides while the heated air exited through the middle. At Ra = 10{dollar}\sp5{dollar} and 5 {dollar}\times{dollar} 10{dollar}\sp5{dollar}, rolls and secondary rolls were observed in the cavity respectively. When the cavity was inclined at 45{dollar}\sp\circ{dollar}, the entrained cold fluid entered the cavity through the two-thirds of the aperture, and the heated air was deflected upwards as it excited through the remaining one-third. The effect of inclining the cavity at 45{dollar}\sp\circ{dollar} caused about 34% increase in average heat transfer coefficient, Nu{dollar}\sb{lcub}\rm ave{rcub}{dollar}, over the horizontal cavity value.;In mixed convection experiment, the approaching cross-flow of cold air deflected the rising heated air downstream. A distinct shear layer with a dividing streamline isolated the cavity and the deflected plume from the free-stream region. For the parameters considered here, Nu{dollar}\sb{lcub}\rm ave{rcub}{dollar} is about 40% of the value obtained for the case of free convection. For the inclined mixed convection, Nu{dollar}\sb{lcub}\rm ave{rcub}{dollar} is four times the value obtained for the horizontal case.;Correlations were obtained for numerical (horizontal) and experimental (horizontal and inclined) free convection in rectangular cavities. The present results compared favourably with those reported in literature.



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