Effects of symmetry on magnetohydrodynamic mixed convection flow in a vertical duct

Abstract

Magnetohydrodynamic convection in a downward flow of liquid metal in a vertical duct is investigated experimentally and numerically. It is known from earlier studies that in a certain range of parameters, the flow exhibits high-amplitude pulsations of temperature in the form of isolated bursts or quasi-regular fluctuations. This study extends the analysis while focusing on the effects of symmetry introduced by two-sided rather than one-sided wall heating. It is found that the temperature pulsations are robust physical phenomena appearing for both types of heating and various inlet conditions. At the same time, the properties, typical amplitude, and range of existence in the parametric space are very different at the symmetric and asymmetric heating. The obtained data show good agreement between computations and experiments and allow us to explain the physical mechanisms causing the pulsation behavior.

Linear instability and nonlinear flow states in a horizontal pipe flow under bottom heating and transverse magnetic field

“…However, in the experiments of Genin et al (2011) and Belyaev et al (2015) for liquid metal flows in a heated horizontal tube under a transverse horizontal magnetic field, unexpected anomalous temperature fluctuations with low frequency and high amplitude are discovered for strong magnetic fields which occur at Re/Ha < 200 when the turbulence is usually regarded to be fully suppressed. Large-amplitude low-frequency pulsations of temperature in the form of isolated bursts or quasi-regular fluctuations have also been observed in experiments (Melnikov et al 2014(Melnikov et al , 2016Kirillov et al 2016;Listratov et al 2016;Belyaev et al 2020) of a downward flow in a vertical round pipe and rectangular duct with one wall heated and an imposed strong magnetic field. The high-amplitude low-frequency fluctuations of velocity and temperature that appear in flows with strong convection and magnetic field effects are proposed to be called magneto-convective fluctuations (Belyaev et al 2021).…”

“…2016; Belyaev et al. 2020) of a downward flow in a vertical round pipe and rectangular duct with one wall heated and an imposed strong magnetic field. The high-amplitude low-frequency fluctuations of velocity and temperature that appear in flows with strong convection and magnetic field effects are proposed to be called magneto-convective fluctuations (Belyaev et al.…”

Experimental study of submerged liquid metal jet in a rectangular duct in a transverse magnetic field

“…Two calibration test sections in the form of straight ducts of rectangular cross-section and (Belyaev et al. 2020), illustrated in figure 6, are used. The section has an inlet in the form of a pipe of mm inner diameter.…”

Transformation of a submerged flat jet under strong transverse magnetic field

“…The accuracy and efficiency of the scheme in simulations of high-Ha parallel shear flows has been demonstrated, e.g., in [8,9,20]. The most recent version of the solver optimized for spatially evolving flows [21] is used in the present study.…”

“…This transformation is preferable to the classical Gauss-Lobatto version because it provides better resolution in the duct's core, which is necessary in our case to accurately reproduce the jet's transformation. Similar coordinate transformations were used in our prior studies of MHD flows with jets [21,22]. One complete simulation of the flow at Re = 20000 and Ha = 1000 is performed.…”