Two-phase stratified MHD flows in rectangular ducts

TL;DR

This paper investigates two-phase stratified MHD flows in rectangular ducts, analyzing how wall conductivity and magnetic field orientation influence flow characteristics, with implications for flow control and engineering applications.

Contribution

It provides the first combined numerical and analytical analysis of two-phase stratified MHD flow in rectangular ducts, highlighting the effects of wall conductivity and magnetic field orientation.

Findings

Flow symmetry is broken by non-conductive gas layers.

Flow characteristics depend strongly on wall-conductivity and magnetic field orientation.

Magnetic Reynolds number has little effect on flow properties.

Abstract

The characteristics of two-phase stratified magnetohydrodynamic (MHD) flow in horizontal rectangular ducts are investigated for a system consisting of a conductive liquid and a non-conductive gas. Numerical and analytical solutions of the governing equations for the velocity and induced magnetic field intensity of fully developed laminar MHD flow are obtained for various combinations of bottom- and side-wall conductivities and for different orientations of an externally applied transverse magnetic field. The relevant set of dimensionless parameters governing the problem is identified. Unlike in single-phase MHD flows, the presence of a non-conductive gas layer breaks the flow symmetry, leading to a significantly different dependence of the flow characteristics on duct aspect ratio, wall-conductivity configuration, and the strength and orientation of the applied magnetic field. Using mercury-air flow as a representative test case, the solutions are employed to quantify the influence of the gas phase on the in-situ liquid holdup, velocity field, pressure gradient, flow lubrication, and pumping-power requirements. It is shown that, regardless of the magnetic Reynolds number, these characteristics are strongly affected by the wall-conductivity configuration and by the orientation of the external magnetic field.