The problem of natural convection from an elliptic tube with its major axis vertical and. i heated uniformly is investigated. The study is based on the solution of full governing equations without boundary layer simplifications. The study focuses on the effect of the I main controlling parameters on both flow and thermal fields. The controlling parameters ! are the modified Rayleigh number, Ra Prandtl number, Pr and axis ratio, Ar. The Ra is considered up to lo7 , the Pr is considered up to 10

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... hile the axis ratio is varied from 0.05 (almost flat plate) to 0.998 ( almost circular cylinder). Results are presented for the local and average Nusselt numbers and local and mean surface temperatures. The study revealed that as Rayleigh number andlor Prandtl number increase the average Nusselt number increases, resulting in a decrease in mean surface temperature. On the other end, the study showed that the effect of axis ratio on the average Nusselt number is not significant with only smaller decrease in average Nusselt number as the axis ratio i increases. 5