Magnetoconvection in a horizontal duct flow — A parametric study

Abstract

Mixed convection flows in a horizontal duct with a heated bottom wall and a magnetic field imposed in the horizontal transverse direction are analyzed numerically using the two-dimensional approximation valid in the limit of strong magnetic field effect. A parametric study is carried out to understand the effect of the Reynolds, Hartmann, and Grashof numbers on the flow. The focus is on the convection instability of the quasi-two-dimensional states that occur under strong magnetic fields. The range of existence of such states is established. Linear stability analysis and simulations of nonlinear regimes demonstrate that high-amplitude low-frequency magnetoconvective fluctuations are generated by the instability in a broad range of parameters and that their strength is not diminished as the magnetic field becomes stronger. Good agreement with experimental data is found.