Natural convection of liquid metal in a vertical annulus with lateral and volumetric heating in the presence of a horizontal magnetic field

Abstract

MHD free convection of a liquid metal is studied in a closed vertical annulus in which the upper and bottom walls are adiabatic while the cylindrical walls are kept at different temperatures. The flow is driven by two mechanisms: the temperature difference between the two cylindrical walls and the volumetric heating. A constant horizontal magnetic field is also imposed resisting the fluid motion. The laminar and turbulent regimes of the flow are assessed by performing three-dimensional direct numerical simulations. The results show that in the absence of the magnetic field, turbulent flow is developed in most of the cases, while as the magnetic field increases the flow becomes laminar. The highest temperature is found in the upper-central part of the annular cavity when the fluid is heated volumetrically, resulting in the creation of two convection currents as the hot fluid ascends in the central part and descends close to both colder walls. The Hartmann and Roberts layers developing near the walls normal and parallel to the magnetic field, respectively, are found to be responsible for the loss of axisymmetry of the present flow. (C) 2011 Elsevier Ltd. All rights reserved.