Three-dimensional numerical simulation of ferrofluid magnetoconvection in cubical enclosure heated with an inner spherical hot block

In this study, three-dimensional computational analysis is performed to investigate the magnetoconvection of ferrofluid ([Formula: see text]-water) within a cubical enclosure heated by an inner spherical hot block. The ferrofluid, considered as a working fluid, is modeled as a single-phase fluid. The inner spherical block is put at high temperature while all the remaining walls of the enclosure are exposed to low temperature. Two radii values ([Formula: see text] and [Formula: see text]) of the inner hot sphere are examined. Governing equations with corresponding boundary conditions are solved numerically applying a second-order accurate finite volume method on a staggered grid system, using an accelerated multigrid model. Simulations are carried out based on various flow-governing parameters such as Rayleigh number [Formula: see text], Hartmann number [Formula: see text] and ferrofluid nanoparticle volume fraction [Formula: see text]. The effects of the pertinent parameters in the performance of the system are also studied. The flow and thermal fields, the local and surface-averaged Nusselt numbers on the sphere and the enclosure for both configurations are detailed. The flow remains steady and laminar for all Rayleigh numbers regardless of the sphere radius. Obviously, heat transfer rate improves with [Formula: see text] augmentation and minimizes with Ha decrease. At the highest Ra and lowest Ha, higher inner sphere radius shows significantly better heat transfer rate (more than [Formula: see text]). Useful correlations are presented to quantify the surface-averaged heat transfer rate through the cubical enclosure.

Symmetry and Asymmetry in the Thermo-Magnetic Convection of Silver Nanofluid

Application of nanofluids is aimed at enhancing the heat transfer performance the same as the utilization of a strong magnetic field. The potential of the combined effect of these passive and active methods was analyzed numerically. The silver nanofluid thermo-magnetic convection in a cubical enclosure placed in the Rayleigh–Benard configuration was investigated for various concentrations of nanoparticles and various values of magnetic induction at constant temperature difference. The nanofluid flow was considered as a two-phase flow and studied with the Euler–Euler approach. The main outcome was related to the heat transfer performance, but also a lot of attention was paid to the flow structure, which is very difficult to obtain by experimental methods. The results exhibited a flow structure with diagonal axis of symmetry in all analyzed cases and stabilizing effect of magnetic field. The heat transfer performance is indicated by the Nusselt number, which increases with an increasing value of magnetic induction but decreases with an increasing concentration of nanoparticles.

Numerical Study of Three- Dimensional Natural Convection in a Differentially Heated Cubical Enclosure

—A high-resolution, finite difference numerical studyis reported on three-dimensional steady-state natural convectionof air, for two Rayleigh numbers, in a cubical enclosure, which isheated differentially at one side walls. The temperature of thewall is TC except for the right vertical wall, in which is TH.Thedetails of the three-dimensional flow and thermal characteristicsare described.