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Olabemiwo, J. T.
Department of Mechanical Engineering, Ladoke Akintola University of Technology
Okekunle, P. O.
Department of Mechanical Engineering, Ladoke Akintola University of Technology
ABSTRACT
The advancement in
research, production, and use of nanofluids presents an opportunity for
improving natural convective heat transfer in cavities. This study involves the
numerical investigation of the natural convection in a two-dimensional
hexagonal cavity fitted with a square obstacle and filled with a ternary hybrid
MgO-ZnO-SiC/ethylene glycol nanofluid under steady state conditions. The
research considered the effects of Rayleigh number, inclination angle, and
aspect ratio on heat transfer and fluid flow in a bid to enhance thermal
efficiency in the complex geometry. The governing Navier-Stokes equations were
solved using the Finite Element Method in COMSOL Multiphysics. The model was
first validated against benchmark results for natural convection in a
differentially heated square cavity for reliability and accuracy. Additionally,
the grid independence validation agrees with results literature which is an
affirmation of the correctness of the numerical model. The results showed a
strong transition from conduction to convection heat transfer as the Rayleigh
number increased. Higher Rayleigh numbers produced stronger buoyancy-driven
circulation, thinner thermal boundary layers, and appreciably high Nusselt
numbers. The average k, Cp,
µ, ρ, α and β were 0.2757449 W/m·K, 2146.9702 J/kg·K, 0.0169729 Pa·s,
1206.50186 kg/m³, 1.41 x 10-05m²/s, and 1.02 x 10-07K-1, respectively. At R𝛼 = 104 and 𝜃 = 0°, 30°, 45°, 60°, and 90°,
Nu values were 4.20, 4.12, 4.15, 4.22, and 4.25, respectively. At R𝛼 = 105
and 𝜃 = 0°, 30°,
45°, 60°, and 90°, Nu values were 5.48, 5.40, 5.42, 5.50, and
5.55, respectively. For
R𝛼 = 102 and AR values of 0.25, 0.3,
0.35, and 0.40, Nu values were 3.50, 3.58, 3.65, and 3.75, respectively. At R𝛼 = 103,
and AR values of 0.25, 0.3, 0.35, and 0.40, Nu
values were 3.55, 3.62, 3.70, and 3.82, respectively. At R𝛼 = 104,
and AR values of 0.25, 0.3, 0.35, and 0.40, Nu
values were 4.05, 4.20, 4.40, and 4.65, respectively. At R𝛼 = 105, and AR values of 0.25, 0.3, 0.35, and 0.40, Nu
values were 4.70, 5.10, 5.55, and 6.00, respectively. The results provide important new information for the design and
optimization of passive cooling applications and natural convection-based
thermal management systems using ternary hybrid nanofluids.
Keywords: Enclosure, Natural Convection, Finite Element Model, Hexagon, Heat Transfer
https://doi.org/10.33922/j.ujet_v12i1_8
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View: 51 | Download: 13
Published
Saturday, February 21, 2026
Issue
Vol. 12, No. 1, March 2026
Article Section
GENERAL
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