THERMAL SCIENCE

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Laminar natural convection of non-Newtonian power-law fluid in an eccentric annulus

ABSTRACT
This work is about studying the natural convection of two-dimensional steady state non-Newtonian power law fluid numerically. The inner cylinder was put eccentrically into the outer one. The cylinders are held at constant temperatures with the inner one heated isothermally at temperature Th and the outer one cooled isothermally at temperature Tc (Th>Tc). The simulations have been taken for the parameters 103≤Ra≤105, 10≤Pr≤103, 0.6≤n≤1.4, 0≤ɛ≤0.9 and an inclination angle ϕ from 0° up to 90°. The average Nusselt numbers for the previous parameters are obtained and discussed numerically. The results revealed that the average Nusselt number has the highest values when n=0.6, Ra=105 at ϕ=0 which is a signal for the large transfer herein and has the lowest values for n=1.4, Ra=103 at ϕ=90° which is a signal that the transfer is by conduction more than convection. Furthermore, the increasing of eccentricity causes an increase in the Nusselt number for all the cases. Finally, the best case where we can get the best heat transfer is at ϕ = 0, ɛ=0.9 among them all. The results have compared with some precedent works and showed good agreement.
KEYWORDS
PAPER SUBMITTED: 2019-08-05
PAPER REVISED: 2019-09-24
PAPER ACCEPTED: 2019-10-30
PUBLISHED ONLINE: 2019-11-17
DOI REFERENCE: https://doi.org/10.2298/TSCI190805424B
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