Three-dimensional simulation of film boiling on a horizontal surface with magnetic field

TL;DR

This paper presents a numerical study of three-dimensional film boiling under magnetic fields, revealing how magnetic field orientation influences vapor flow patterns and heat transfer in magnetohydrodynamic conditions.

Contribution

It introduces a combined sharp phase-change and electromagnetic force model to analyze magnetic field effects on film boiling patterns and heat transfer.

Findings

Vertical magnetic fields produce isotropic vapor jets.

Horizontal magnetic fields create anisotropic vapor sheets.

Magnetic fields suppress flow vortices and alter boiling dynamics.

Abstract

This study conducts a numerical investigation into the three-dimensional film boiling of liquid under the influence of external magnetic fields. The numerical method incorporates a sharp phase-change model based on the volume-of-fluid approach to track the liquid-vapor interface. Additionally, a consistent and conservative scheme is employed to calculate the induced current densities and electromagnetic forces. We investigate the magnetohydrodynamic effects on film boiling, particularly examining the pattern transition of the vapor bubble and the evolution of heat transfer characteristics, exposed to either a vertical or horizontal magnetic field. In single-mode scenarios, film boiling under a vertical magnetic field displays an isotropic flow structure, forming a columnar vapor jet at higher magnetic field intensities. In contrast, horizontal magnetic fields result in anisotropic flow, creating a two-dimensional vapor sheet as the magnetic strength increases. In multi-mode scenarios, the patterns observed in single-mode film boiling persist, with the interaction of vapor bubbles introducing additional complexity to the magnetohydrodynamic flow. More importantly, our comprehensive analysis reveals how and why distinct boiling effects are generated by various orientations of magnetic fields, which induce directional electromagnetic forces to suppress flow vortices within the cross-sectional plane.