Abstract
Melting phenomena occurs in various industrial applications, such as metal castings of turbine blades, environmental engineering, PCM-based thermal storage devices, etc. During the design of these devices, they are designed for efficient heat transfer rate. To improve the heat transfer rate, understanding of the important flow processes during the melting (and solidification) is necessary. An objective of the present work is to study the effect of natural convection and magnetic field on interface morphology and thereby on melting rate. In this work, therefore, an effect of uniform transverse magnetic field on the melting inside a cavity, filled initially with solid gallium, at various Rayleigh numbers (Ra=3×105, 6×105, and 9×105) is presented. A 2D unsteady numerical simulation, with the enthalpy-porosity formulation, is performed using ANSYS-Fluent. The magnetic field is characterized by the Hartmann number (Ha) and the results are shown for the Ha = 0, 30 and 50. The horizontal walls of the cavity are considered insulated and vertical walls are respectively considered hot and cold. It is observed that the role of natural convection during the melting is significant on the temperature distribution and solid-liquid interface. The increased magnetic field (Ha = 30 and 50) found to have a suppressing effect on the dominance of natural convection at all Rayleigh numbers (Ra=3×105, 6×105, and 9×105).
Highlights
Melting occurs in metal castings of turbine blades, environmental engineering, PCM-based thermal storage devices, nuclear reactor systems, materials processing, solar energy systems, etc. [1]
Two-dimensional unsteady numerical simulations are performed to study an effect of a uniform horizontal magnetic field on melting inside a cavity filled initially with a solid gallium at various Rayleigh numbers (Ra=3×105, 6×105, and 9×105) the Hartmann number (Ha = 0, 30 and 50) using ANSYS-Fluent with the enthalpy-porosity formulation
The simulation results are produced in terms of solid-liquid interface, contours of streamlines, temperature and velocity magnitude and average Nusselt number on the hot wall
Summary
Melting occurs in metal castings of turbine blades, environmental engineering, PCM-based thermal storage devices, nuclear reactor systems, materials processing, solar energy systems, etc. [1]. Melting occurs in metal castings of turbine blades, environmental engineering, PCM-based thermal storage devices, nuclear reactor systems, materials processing, solar energy systems, etc. To improve the melting rate and heat transfer efficiency, understanding of the important flow processes is necessary. The natural convection, for example, can affect the liquid-solid interface morphology. If the liquid is electrically conducting the interface morphology depend on the interaction of the buoyancy force and Lorentz force. The imposed magnetic field can control the melting rate in the electrically conducting fluid. There is considerable interest in studying the physics that affect the rate of melting (or solidification) preferably inside a rectangular enclosure
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