Numerical Predictions of Momentum and Heat Transfer Characteristics from a Heated Sphere in Yield-Stress Fluids
2013
Nirmalkar, N. | Chhabra, R. P. | Poole, R. J.
In this work, momentum and heat transfer characteristics of a heated sphere immersed in visco-plastic media have been studied over a wide range of conditions: plastic Reynolds number, 1 ≤ Re ≤ 100, Prandtl number, 1 ≤ Pr ≤ 100, and Bingham number, 0 ≤ Bn ≤ 10⁴. The equations of motion and energy have been solved numerically to elucidate the influence of each of these dimensionless parameters on the local characteristics like streamlines, isotherms, kinematics of flow, local Nusselt number, etc. as well as on the gross engineering parameters such as drag coefficient and surface average Nusselt number. Furthermore, a detailed examination of the so-called yielded (fluid-like) and unyielded (solid-like) regions in the flow domain is carried out as a function of both the Reynolds and Bingham numbers. The present results have been compared with the scant results available in the literature and these are found to be in good agreement. Finally, the present numerical results for drag and Nusselt number (in the form of the so-called j-factor) have been correlated with the modified Bingham and Reynolds number via simple expressions thereby enabling their interpolation for the intermediate values of these dimensionless parameters.
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