Natural Convection and Entropy Generation in Nanofluid Filled Entrapped Trapezoidal Cavities under the Influence of Magnetic Field

Abstract

Abstract:In this article, entropy generation due to natural convection in entrapped trapezoidal cavities filled with nanofluid under the influence of magnetic field was numerically investigated. The upper (lower) enclosure is filled with CuO-water (Al 2 O 3 -water) nanofluid. The top and bottom horizontal walls of the trapezoidal enclosures are maintained at constant hot temperature while other inclined walls of the enclosures are at constant cold temperature. Different combinations of Hartmann numbers are imposed on the upper and lower trapezoidal cavities. Numerical simulations are conducted for different values of Rayleigh numbers, Hartmann number and solid volume fraction of the nanofluid by using the finite element method. In the upper and lower trapezoidal cavities magnetic fields with different combinations of Hartmann numbers are imposed. It is observed that the averaged heat transfer reduction with magnetic field is more pronounced at the highest value of the Rayleigh number. When there is no magnetic field in the lower cavity, the averaged Nusselt number enhances as the value of the Hartmann number of the upper cavity increases. The heat transfer enhancement rates with nanofluids which are in the range of 10% and 12% are not affected by the presence of the magnetic field. Second law analysis of the system for various values of Hartmann number and nanoparticle volume fractions of upper and lower trapezoidal domains is performed.

Effect of a Magnetic Quadrupole Field on Entropy Generation in Thermomagnetic Convection of Paramagnetic Fluid with and without a Gravitational Field

“…Such irreversibilities may be caused by heat transfer across the finite temperature gradient, viscous dissipation and magnetic field effects, etc. The magnetic field influence on entropy generation in nanofluid-filled cavities has been exposed in the recent literature [26][27][28]. The results showed that the magnetic field and the presence of nanoparticle had a substantial influence on flow pattern, heat transfer, and entropy generation.…”

Entropy Generation and Heat Transfer Performances of Al2O3-Water Nanofluid Transitional Flow in Rectangular Channels with Dimples and Protrusions

“…Matin et al [44] accomplished a numerical research on MHD mixed convection flow using SiO2-water nanofluids over a non-linear stretching sheet. Selimefendigil et al [45] carried out an investigation on entropy generation of nanofluids natural convection in entrapped trapezoidal cavities taking the influence of magnetic field into consideration. According to Singh et al [30], from the view point of decreasing entropy generation, the Al2O3-water nanofluids behaves better in conventional channels and minichannels under laminar flow, and similar behavior can be found in minichannels and microchannels under turbulent flow, which indicates the significant influences of nanofluids flow regime and channel size on entropy generation.…”

“…Matin et al [44] accomplished a numerical research on MHD mixed convection flow using SiO 2 -water nanofluids over a non-linear stretching sheet. Selimefendigil et al [45] carried out an investigation on entropy generation of nanofluids natural convection in entrapped trapezoidal cavities taking the influence of magnetic field into consideration.…”

Analysis of Natural Convection Flow in a Trapezoidal Cavity Containing a Rectangular Heated Body in Presence of External Oriented Magnetic Field

“…They also studied numerical analysis of heat generation effect on natural convection flow in a trapezoidal cavity containing a rectangular heated body [4]. Selimefendigil et al [5] investigated entropy generation due to natural convection in entrapped trapezoidal cavities filled with nanofluid under the influence of magnetic field where the upper (lower) cavity is filled with CuO-water (Al 2 O 3 -water) nanofluid and the top and bottom horizontal walls of the trapezoidal cavities are maintained at constant hot temperature while other inclined walls of the enclosures are at constant cold temperature and also different combinations of Hartmann numbers are imposed on the upper and lower trapezoidal cavities. It is found that the heat transfer enhancement rates with nanofluids which are in the range of 10% and 12% are not affected by the presence of the magnetic field.…”