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Simulation and analysis of turbulent MHD channel flow with a streamwise magnetic field
Author(s) -
Krasnov Dmitry,
Boeck Thomas
Publication year - 2016
Publication title -
pamm
Language(s) - English
Resource type - Journals
ISSN - 1617-7061
DOI - 10.1002/pamm.201610304
Subject(s) - physics , turbulence , prandtl number , mechanics , hartmann number , magnetic prandtl number , magnetohydrodynamics , reynolds number , magnetic field , magnetic reynolds number , open channel flow , flow (mathematics) , classical mechanics , heat transfer , quantum mechanics , nusselt number
We perform large‐eddy simulations of turbulent MHD channel flow with a streamwise magnetic field using a pseudo spectral method. The streamwise magnetic field leads to turbulent drag reduction due to the selective Joule damping of certain flow structures. Near the walls, the turbulent mean velocity profile retains the logarithmic layer but the von Karman constant decreases with increasing magnetic field strength. In the outer region, the flow is characterized by persistent streaky structures of large streamwise extent, which lead to a rather flat mean velocity profile. In addition, the streamwise velocity fluctuations develop a pronounced second peak upon increasing the magnetic induction as well as a second logarithmic layer that increases in steepness. We find that Prandtl's classical mixing‐length model with a variable Kármán constant can describe the modified logarithmic layer reasonably accurately in a wide range of Reynolds and Hartmann numbers. However, the flow modification near the center of the channel is not properly captured by this approach. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)