Numerical investigation of conjugate heat transfer and entropy generation of MHD natural convection of nanofluid in an inclined enclosure

Purpose The purpose of this paper is to investigate conjugate heat transfer of natural convection and entropy generation of nanofluid in the presence of external magnetic field via numerical approach in an inclined square cavity enclosure. Design/methodology/approach Control volume finite volume method with collocated arrangement of grids was used for discretization of continuity, momentum, solid and fluid energy equations. Rhie and Chow interpolation technique was applied to avoid checkerboard problem in pressure field and the well-established SIMPLE algorithm was followed to deal with the pressure and velocity coupling. The cavity is filled with water and nanoparticles of the aluminum oxide (Al2O3). This study has been conducted for the certain pertinent parameters of the volume fraction of nanoparticle (φ = 0–0.08), the angle of inclination (ϴ = 0°–330°), the Ra number (Ra = 103–108), the solid to fluid conductivity ratio (ksf = 1–400), the Ha number (Ha = 0–80) and the wall thickness ratio (δ/L = 0–0.3). Findings The results indicate that averaged Nu number increases by approximately 9% by increasing volume fraction from 0.0 to 0.08. Nu increases with an increasing inclination angle to 40° and decreases abruptly in 90° because of the formation of two weaker vorticity with opposite circulation pattern intensifying the density of isotherm curves in a vertical direction. Nu increases sharply with increasing Ra more than 105. Nu also augments almost 67% by increasing ksf = 1 to ksf = 50 and remains constant by increasing ksf more than 50. Nu number reduction is almost 72% with a variation of wall thickness ratio from d/L = 0 to 0.3. Entropy generation because of fluid flow, magnetic field and heat transfer reduces linearly almost 30%, 19% and 16% by increasing volume fraction, respectively. With increasing ksf, entropy generation because of fluid flow, magnetic field and heat transfer increases asymptotically, but Bejan number decreases. Originality/value A brief review of conducted research studies in nanofluid flow and heat transfer reveals that the effect of wall thermal inertia was not investigated in MHD natural convection of nanofluids in an inclined enclosure. The aim of the present study is to analyze conjugate heat transfer in an inclined cavity filled with water and Al2O3.

Numerical Investigation of Magneto-Natural Heat Transfer in Nanofluid Filled Inclined Enclosure

This paper examines the natural convection in an inclined enclosure that is filled with a water-copper nanofluid and influenced by a magnetic field applied normal to the plane of the cavity. The horizontal walls are assumed to be insulated while the side vertical walls of the cavity are heated differentially. The governing equations are re-formulated in functions of stream function and vorticity. The resulting boundary value problem is solved numerically using an ADI method (alternating direction implicit). A variety of plots showing the velocity and temperature profiles and the influence of Hartmann number as well as Rayleigh number on the streamlines and isotherms are shown.

Numerical study on convective flow and heat transfer in 3D inclined enclosure with hot solid body and discrete cooling

Purpose This study aims to deal the numerical simulation on buoyant convection and energy transport in an inclined cubic box with diverse locations of the heater and coolers. Design/methodology/approach The left/right walls are cooled partially whereas the other walls are kept adiabatic. In the left/right walls, three different locations of the cooler are examined, whereas heater moves in three locations in the middle of the enclosed box. The governing models are numerically solved using the finite-element method. Findings The simulations are done on several values of the Rayleigh number and cavity inclination angles and different locations of the heater and coolers. The results are presented in the form of streamlines, isosurfaces and Nusselt numbers for different values of parameter involved here. It is recognized that the inclination of the box and the locations of the coolers strongly influence the stream and energy transport inside the enclosed domain. Research limitations/implications The present investigation is conducted for steady, laminar, three-dimensional natural convective flow in a box for different locations of cooler and tilting angles of a cavity. The study might be useful to the design of solar collectors, room ventilation systems and electronic cooling systems. Originality/value This work examines the effects of different locations of cooler and tilting angles of a cavity on convective heat transfer in a 3D cavity. The study is useful for thermal engineering applications.

MHD convection flow of Ag–water nanofluid in inclined enclosure with center heater

ABSTRACT Simulations are performed to examine magnetohydrodynamic convection of an Ag–water nanofluid within an inclined enclosure containing a center heater oriented in different directions. In performing the analysis, the left and right vertical walls are assumed to be isothermally cooled, while the bottom wall is isothermally heated and the top wall is adiabatic. The governing equations are solved numerically using the finite-volume method. The simulations focus on the effects of the Rayleigh number (Ra = 104, 105 and 106), Hartmann number (Ha = 0, 25 and 50), inclination angle (γ = 0°, 45°, 90° and 135°), orientation of heater (horizontal or vertical) and internal heat generation (S = 0, 10 and 20) on the convective heat transfer performance within the enclosure. The results show that the heat transfer performance is dominated by the inclination angle of the enclosure and the Hartmann number. In particular, the heat transfer rate reduces as inclination angle and Hartmann number increase. The maximum heat transfer performance is obtained with a vertical center heater, an inclination angle of γ = 45° and a Rayleigh number of Ra = 106. It is additionally shown that the heat transfer performance improves with an increasing volume fraction of nanoparticles.