Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Steady, laminar, developing natural convective flow in vertical and inclined open-ended ducts was studied by the author using a Mach-Zehnder interferometer. Square ducts were considered. The ducts were isothermal, and heated to a temperature above that of the ambient fluid (air).;This study was unique in two respects; almost no information is available at present on natural convective flow in inclined ducts, and to the best of the authors' knowledge this is the first heat transfer study to employ an interferometer with the test beam traversing the heated model in a direction which was not horizontal.;Test beam averaged Nusselt numbers, and average Nusselt numbers are presented for the ducts under investigation. The most significant effects of inclining the ducts are to cause two rolls to form in the developing length of the duct, and to reduce the heat transfer rates on the upper region and increase those on the lower region of the tube and duct surface.;In addition to these experimental results, numerical solutions for fully developed flow in inclined ducts were presented. Two thermal boundary conditions were considered; isothermal as well as a duct with one side heated and the opposite side cooled. The solution for fully developed flow in inclined isothermal ducts are identical to that of vertical isothermal ducts provided the Rayleigh number contains the cosine of the angle of inclination.



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