Abstract
The current paper presents a numerical study of the magnetohydrodynamics natural convection and entropy production of Cu–water nanofluid contained in a porous annulus between a heated Koch snowflake and wavy cylinder with lower temperature with respect to the Koch snowflake. The numerical algorithm is based on the Galerkin Finite Element Method. The impacts of Rayleigh number (Ra = 103, 104, 105, and 106), Hartman number (Ha = 0, 25, 50, and 100), Darcy number (Da = 10−2, 10−3, 10−4, and 10−5), nanoparticle volumetric fraction (φ = 2%, 3%, 4%, and 5%), and the undulations number of the outer wavy cylinder (three cases) on the distributions of isotherms, streamlines, mean Nusselt number (Nuavg), as well as on total entropy production and Bejan number are thoroughly examined. The computational outcomes disclose that dispersing more Cu nanoparticles in the base fluid and creating a flow with higher intensity inside the annulus by raising the Rayleigh number bring about a boosted natural convective flow in the cavity, which improves the heat transmission rate. In addition, it can be noted that owing to the peculiar form of the heated Koch snowflake, nanofluid gets trapped between the angled parts, resulting in uneven temperature profiles with higher values in these places.
Highlights
Introduction published maps and institutional affilConvective heat transfer via a mix of materials has become an important technique in a range of industrial and residential applications, including building heating and cooling, thermal management of electronic components, systems of heat exchange, and solar energy.Several researchers have examined the characteristics of fluid flow and heat transmission in numerous technical applications [1,2,3,4]
The results suggest that employing the multi-layered porous material limits the extension of flow vortices near the moving walls, increasing heat transmission by up to 17%
This paper presents the flow behavior of free convection heat transmission in a copper water-based nanofluid in a porous annulus consisting of a cold wavy wall cylinder and a heated Koch snowflake-shaped wall cylinder
Summary
Two-dimensional, unsteady, laminar natural convection flow in an annulus bordered by a Koch snowflake and a wavy cylinder is analyzed. L/2 is saturated with a Newtonian nanofluid. Thermal equilibrium is considered between nanoparticles representing the solid phase and water representing the liquid phase, and both water and nanoparticles have the same motion (i.e., same magnitude and direction of flow). The effects of Joule heating, viscous dissipation, and displacement currents are deemed insignificant. With regard to the transport procedures, the following assumptions are considered:
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