Magnetoconvection in a horizontal duct flow at very high Hartmann and Grashof numbers

Direct numerical simulations and linear stability analysis are carried out to study mixed convection in a horizontal duct with constant-rate heating applied at the bottom an imposed transverse magnetic field. A two-dimensional approximation corresponding asymptotic limit of very strong field effect is validated applied, together full three-dimensional analysis, investigate flow's behaviour previously unexplored range control parameters typical conditions liquid metal blanket nuclear fusion reactor (Hartmann numbers up $10^4$ Grashof $10^{10}$ ). It found that instability quasi-two-dimensional rolls parallel discovered smaller Hartmann earlier studies also occurs this parameter range. Transport by mean flow leads magnetoconvective temperature fluctuations exceptionally high amplitudes. demonstrated structure flows does not guarantee accuracy classical approximation. The deteriorates highest considered study.