Decay of turbulence in a liquid metal duct flow with transverse magnetic field. (25th May 2019)

• Record Type: Journal Article
• Authors: Zikanov, Oleg; Krasnov, Dmitry; Boeck, Thomas; Sukoriansky, Semion
• Is Part Of: Journal of fluid mechanics. Volume 867(2019)
• Page Start: 661
• Page End: 690
• Publication Date: 2019-05-25
• Subjects: high-Hartmann-number flows, -- MHD turbulence, -- turbulence simulation; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2019.171
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract : Decay of honeycomb-generated turbulence in a duct with a static transverse magnetic field is studied via direct numerical simulations. The simulations follow the revealing experimental study of Sukoriansky et al. ( Exp. Fluids, vol. 4 (1), 1986, pp. 11–16), in particular the paradoxical observation of high-amplitude velocity fluctuations, which exist in the downstream portion of the flow when the strong transverse magnetic field is imposed in the entire duct including the honeycomb exit, but not in other configurations. It is shown that the fluctuations are caused by the large-scale quasi-two-dimensional structures forming in the flow at the initial stages of the decay and surviving the magnetic suppression. Statistical turbulence properties, such as the energy decay curves, two-point correlations and typical length scales are computed. The study demonstrates that turbulence decay in the presence of a magnetic field is a complex phenomenon critically depending on the state of the flow at the moment the field is introduced.