Bejan flow visualization of free convection in a Jeffrey fluid from a semi-infinite vertical cylinder : influence of Deborah and Prandtl numbers

Kumar, M; Reddy, GJ; Beg, OA

Abstract

This article studies the pattern of heat lines in free convection non-Newtonian flow from a
semi-infinite vertical cylinder via Bejan’s heat function concept. The viscoelastic Jeffrey fluid
model is employed. The time-dependent, coupled, non-linear conservation equations for
momentum and energy (heat) are solved computationally with the unconditionally stable finite
difference Crank-Nicolson method. Extensive graphical results are presented for the influence
of Deborah number (viscoelastic parameter) and Prandtl number (with ranges 0 - 0.8 and 0.68
- 7.2, respectively) on thermal and flow characteristics including time histories of overall skin friction
and heat transfer rate. Lower values of Deborah number indicate that the material acts
in a more fluid-like manner whereas the higher values of Deborah number correspond to the
material showing characteristics more associated with a solid. The solutions indicate that the
time taken for the flow-field variables to achieve the steady-state is increased with higher
values of Deborah number. Boundary flow visualization is presented using heat lines,
isotherms and streamlines. It is observed that as Deborah number increases the intensity of heat
lines increases and they tend to deviate from the hot cylindrical wall. Furthermore, the flow field
variables for the Newtonian fluid case exhibit a significantly different pattern from that
of Jeffrey fluid.

Citation

Kumar, M., Reddy, G., & Beg, O. (2019). Bejan flow visualization of free convection in a Jeffrey fluid from a semi-infinite vertical cylinder : influence of Deborah and Prandtl numbers. Journal of Thermal Analysis and Calorimetry, 138, 531-543. https://doi.org/10.1007/s10973-019-08099-7

• Journal Article Type: Article
• Acceptance Date: Feb 14, 2019
• Online Publication Date: Mar 28, 2019
• Publication Date: Oct 1, 2019
• Deposit Date: Apr 1, 2019
• Publicly Available Date: Mar 28, 2020
• Journal: Journal of Thermal Analysis and Calorimetry: An International Forum for Thermal Studies
• Print ISSN: 1388-6150
• Electronic ISSN: 1588-2926
• Publisher: Springer Verlag
• Volume: 138
• Pages: 531-543
• DOI: https://doi.org/10.1007/s10973-019-08099-7
• Publisher URL: https://doi.org/10.1007/s10973-019-08099-7
• Related Public URLs: https://link.springer.com/journal/10973
• Additional Information: Projects : Heat and flow visualization of non-Newtonian coating flows