Dynamics of liquid metal channel flow in a transverse magnetic field with buoyancy forces

Abstract

In this study, Large Eddy Simulations (LES) are employed to investigate the fundamental interplay between magnetic fields and thermal convection in a vertical, turbulent, liquid metal channel flow. The primary focus is on understanding the modifications to mean flow characteristics and higher-order statistical properties. This interaction leads to significant modifications to the turbulent flow structures, resulting in directional dependencies in the flow properties. The calculations are conducted at a friction Reynolds number of Re_τ≈395, Hartmann number (Ha) in the range of 0≤Ha≤15, and Richardson number (Ri) varying between 0 and 0.05. We reveal that the presence of a wall-normal magnetic field in this particular setup suppresses turbulent kinetic energy, while buoyancy forces counteract this effect, promoting turbulence and introducing asymmetry into the statistical properties of the flow. Moreover, the magnetic field induces a preferential alignment of both vortical structures and near-wall streaks. The correlation analysis discovers a stretch of the longitudinal scales, while the spectral analysis indicates that both the magnetic field and buoyancy forces affect the distribution of turbulent kinetic energy at different scales. Notably, at Ha=15, the two-dimensional (2D) energy spectrum function has a slope similar to that predicted by the κ⁻³ law in the inertial range. This deviation of mechanism from “classical” turbulence scaling suggests that the applied magnetic field alters the energy cascade, primarily due to enhanced Joule dissipation.