Natural convection in horizontal pipe flow with a strong transverse magnetic field

Linear stability analysis and direct numerical simulations are conducted to analyse mixed convection in a liquid metal flow in a horizontal pipe with imposed transverse magnetic field. The pipe walls are electrically insulated and subject to constant flux heating in the lower half. The results reveal the nature of anomalous temperature fluctuations detected in earlier experiments. It is found that, at the magnetic field strength far exceeding the laminarization threshold, the natural convection develops in the form of coherent quasi-two-dimensional rolls aligned with the magnetic field. Transport of the rolls by the mean flow causes high-amplitude, low-frequency fluctuations of temperature.