Analysis of entropy generation in natural convection of nanofluid inside a square cavity having hot solid block: Tiwari and Das' model

A computational work has been performed in this study to investigate the effects of solid isothermal partition insertion in a nanofluid filled cavity that is cooled via corner isothermal cooler. Mathematical model formulated in dimensionless primitive variables has been solved by finite volume method. The study is performed for different geometrical ratio of solid inserted block and corner isothermal cooler, Rayleigh number and solid volume fraction parameter of nanoparticles. It is observed that an insertion of nanoparticles leads to enhancement of heat transfer and attenuation of convective flow inside the cavity

Mixed convection–radiation in lid‑driven cavities with nanofluids and time‑dependent heat‑generating body

The cooling process of electronic devices having heat-generating elements is a major challenge allowing to develop electronics industry. Therefore, a creation of novel cooling techniques is an important task that can be solved numerically taking into account the multiparametric character of this problem. The mixed convection heat transfer combined with thermal radiation in a lid-driven cavity filled with an alumina–water nanofluid under the effect of sinusoidal time-dependent heat-generating solid element is studied numerically. The partial differential equations formulated in stream function–vorticity variables are solved by the finite difference method. Effects of the Rayleigh number, Reynolds number, thermal radiation parameter, heater location, volumetric heat flux oscillation frequency and nanoparticles volume fraction on liquid flow and heat transfer are analyzed. It has been found that an addition of nanoparticles leads to reduction of the heater temperature, while convective flow rate decreases also

Effects of Arc-Shaped Partitions in Corners of a Shallow Cavity on Natural Convection

I n this study, a numerical analysis carried out to determine the effects of arc-shaped partitions in corners of a shallow cavity on heat transfer which is natural convection and fluid flow. Partitions are accepted as conductive and two different partitions materials are chosen as wood and aluminum. The finite volume approach is used to discretize the governing equations for Rayleigh numbers Ra and shape ratio of the arc-shaped partition. It is found that arc-shaped partitions have effect on characteristic parameters of fluid flow and heat transfer. Specially, aluminum arc-shaped partition affects the average heat transfer enhancement, because it has high heat transfer coefficient. Also, possibilities of occurring dead regions are examined and streamlines obtained for without partitions and high Rayleigh numbers which are Ra=105 and Ra=106 show that dead regions occur in corners of the shallow cavity. Results obtained from the analysis using partitions and considering different Rayleigh numbers and partition materials show that using partition which is arcshaped prevent occurring dead region

Numerical study of periodic magnetic field effect on 3D natural convection of MWCNT-water/nanofluid with consideration of aggregation

In this paper, a numerical study is performed to investigate the effect of a periodic magnetic field on three-dimensional free convection of MWCNT (Mutli-Walled Carbone Nanotubes)-water/nanofluid. Time-dependent governing equations are solved using the finite volume method under unsteady magnetic field oriented in the x-direction for various Hartmann numbers, oscillation periods, and nanoparticle volume fractions. The aggregation effect is considered in the evaluation of the MWCNT-water/nanofluid thermophysical properties. It is found that oscillation period, the magnitude of the magnetic field, and adding nanoparticles have an important effect on heat transfer, temperature field, and flow structure. © 2019 by the authors

A finite element analysis on combined convection and conduction in a channel with a thick walled cavity

Purpose: The purpose of this paper is to examine the effects of thick wall parameters of a cavity on combined convection in a channel. In other words, conjugate heat transfer is solved. Design/methodology/approach: Galerkin weighted residual finite element method is used to solve the governing equations of mixed convection. Findings: The streamlines, isotherms, local and average Nusselt numbers are obtained and presented for different parameters. It is found heat transfer is an increasing function of dimensionless thermal conductivity ratio. Originality/value: The literature does not have mixed convection and conjugate heat transfer problem in a channel with thick walled cavity

Computational analysis of mixed convection in a channel with a cavity heated from different sides.

A computational work is performed in this paper to analyze the heat transfer, temperature distribution and flow field in a channel with a cavity heated from different sides. Flow inlets to the channel are uniform. Constant magnetic field is applied to the channel as Ha = 10, Prandtl number is chosen as Pr = 0.7 and Reynolds number is fixed at Re = 100. Finite element method is used to solve governing equations. Three different cases were considered based on heater position in the cavity at the left vertical side (Case 1), bottom side (Case 2) and right vertical side (Case 3). It is found that the highest heat transfer is obtained when the isothermal heater is located at the right vertical wall

Entropy Generation Due to Magneto-Convection of a Hybrid Nanofluid in the Presence of a Wavy Conducting Wall

The two-dimensional, time-independent conjugate natural convection flow and entropy generation are numerically investigated in three different cases of a wavy conducting solid block attached to the left wall of a square cavity. A hybrid nanofluid with titania (TiO2) and copper (Cu) nanoparticles and base fluid water in the fluid part is considered in the presence of a uniform inclined magnetic field. The leftmost wall of the cavity is the hot one and the rightmost one is the cold one. Radial-basis-function-based finite difference (RBF-FD) is performed on an appropriate designed grid distribution. Numerical results in view of streamlines and isotherms, as well as average Nusselt number in an interface and total entropy generation are presented. The related parameters such as Hartmann number, Rayleigh number, conductivity ratio, amplitude in wavy wall, number of waviness, and inclination angle of magnetic field are observed. Convective heat transfer in the fluid part is an increasing function of kr,Ra,γ, while it deflates with the rise in Ha in each case. Total entropy generation increases with the increase in Ra and kr but it decreases with Ha values. Average Bejan number ascends with the rise in Ha and descends with the rise in Ra