Effect of Orientation on Mixed Convection from a Heated Square Bar in Newtonian and Power-Law Fluids

Abstract

In this work, mixed convective heat transfer from a heated square bar at an incidence of 45° in power-law fluids has been investigated numerically in the so-called aiding buoyancy configuration. The governing differential equations have been solved over the following ranges of conditions: Richardson number, 0 ≤ Ri ≤ 2, power-law index, 0.2 ≤ n ≤ 1, Reynolds number, 1 ≤ Re ≤ 40, and Prandtl number, 0.7 ≤ Pr ≤ 100. The detailed flow and heat transfer characteristics have been visualized in terms of the streamline and isotherm contours adjacent to the surface of the heated cylinder. The macroscopic heat and momentum transfer characteristics, like local and average values of the Nusselt number (Nu) and drag coefficients (CD), have been analyzed as functions of the Reynolds number (Re), Prandtl number (Pr), Richardson number (Ri), and power-law index (n). Further insights are provided in terms of the distribution of the pressure coefficient and local Nusselt number along the surface of the tilted square. As expected, the value of the local Nusselt number decreases from its maximum value at the front stagnation point along the surface of the bar. Over the range of conditions spanned here, the flow is steady and symmetric about the vertical centerline. Finally, the present numerical values of the average Nusselt number are correlated using a nonlinear regression approach which facilitates interpolation of the present results for the intermediate values of the governing parameters.