In many situations, heat transfer occurs primarily by free convection, such as that in confined and restricted spaces and/or where it is not possible to induce fluid motion by using a pump or impeller. In this work, natural convection from an isothermal cone in power law and Bingham plastic fluids has been investigated numerically by solving the coupled momentum and energy equations over wide ranges of conditions such as the Grashof number ( 10 10 4 ), the Prandtl number (5–100), the Bingham number (1–50), and the power-law index (0.4–1). The structure of the flow and temperature fields is visualized in terms of streamlines and isotherm contours, yielded and unyielded regions, and the variation of the local Nusselt number along the surface of the cone. The location and shape of the yielded and unyielded regions are influenced by the values of the Grashof and Bingham numbers. The size of the unyielded regions progressively decreases with the increasing Bingham number, whereas the Grashof number promotes the growth of fluidlike regions. Shear-thinning fluid behavior promotes heat transfer with reference to that in Newtonian fluids. On the other hand, the Bingham yield stress has an adverse influence on the overall heat transfer. The present values of the average Nusselt number are correlated in terms of the pertinent dimensionless numbers to enable its prediction in a new application. Finally, a criterion for the onset of convection in Bingham fluid is also reported in terms of B n max 0.15 G r BP ; above which, conduction is the main mode of transport. Thus, the relative magnitudes of the buoyancy and viscous (including the contribution of yield stress) forces determine the degree of deterioration in the rate of heat transfer with reference to that in Newtonian fluids otherwise under identical conditions. This information is valuable: not only in designing heat transfer equipment, but also in the processing of temperature-sensitive materials.


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    Title :

    Free Convection from a Heated Vertical Cone in Generalized Newtonian Fluids


    Contributors:
    Mishra, P. (author) / Nirmalkar, N. (author) / Chhabra, R. P. (author)

    Published in:

    Publication date :

    2019-04-12


    Size :

    14 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English