Effect of the three main directions of an external magnetic field on the free convection in Fe3O4- water nanofluid filled cubic enclosure
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Date
2021-04-21
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9th EUROPEAN CONFERENCE ON RENEWABLE ENERGY SYSTEMS
Abstract
The present work studies numerically the influence of the three main directions of an external magnetic field on Fe3O4-water nanofluid free convective flow within a cubic enclosure subjected to horizontal temperature gradient. The MHD problem is mathematically modeled, and its dimensionless equations are established. The system of partial differential equations, governing the phenomenon, is resolved by a numerical approach based on the finite volume method using ANSYS Fluent. The impact of Rayleigh number (10^3≤Ra≤10^6 ), Hartmann number (0≤Ha≤20) and the three principal magnetic field directions on thermo-hydrodynamics behavior of nanofluid is also studied. This study is carried out for pure water (∅=0) and for a nanofluid with low solid volume fraction (∅=0.02). The correlations chosen for calculating thermal conductivity and dynamic viscosity are specifically developed for Fe3O4-water nanofluid from previous experimental studies. Simulation results reveal that the decrease of Nusselt number with increasing magnetic field strength becomes stronger with increasing the Ra number. Applying magnetic field horizontally i.e. parallel to the temperature gradient, decreases heat transfer greater than in the other two directions. In second position, the most significant reduction in convective heat transfer rate is recorded when magnetic field direction is vertical i.e. parallel to gravity.