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Magnetohydrodynamic drag reduction and its efficiency

Shatrov, V.; Gerbeth, G.

We present results of direct numerical simulations of a turbulent channel flow influenced by electromagnetic forces. The magnetohydrodynamic Lorentz force is created by the interaction of a steady magnetic field and electric currents fed to the fluid via electrodes placed at the wall surface. Two different cases are considered. At first, a time-oscillating electric current and a steady magnetic field create a spanwise time-oscillating Lorentz force. In the second case, a stationary electric current and a steady magnetic field create a steady, mainly streamwise Lorentz force. Besides the viscous drag, the importance of the electromagnetic force acting on the wall is figured out. Regarding the energetic efficiency it is demonstrated that in all cases a balance between applied and flow induced electric currents improves the efficiency significantly. But even then, the case of a spanwise oscillating Lorentz force remains with a very low efficiency, whereas for the self-moved regime in case of a steady streamwise force much higher efficiencies are found. Still, no set of parameters has yet been found for which an

energetic breakthrough, i.e. a saved power exceeding the used power, is reached.

  • Physics of Fluids 19, 035109(2007)

Permalink: https://www.hzdr.de/publications/Publ-8594
Publ.-Id: 8594