NUMERICAL SIMULATIONS OF TIME-DEPENDENT HUNT FLOWS WITH FINITE WALL CONDUCTIVITY

The transition from laminar to time dependent magnetohydrodynamic duct flows with finite electrically conducting Hartmann walls and insulating side walls is investigated. The linear stability limit is determined based on the procedure presented in [2]. Based on these results, numerical simulations with OpenFOAM are performed for Hartmann numbers 500 <= Ha <= 2000, Reynolds numbers 300 <= Re <= 12000 and with the wall conductance ratio c= 0.03. Simulations show that the so-called Ting & Walker (TW) vortices, which form at the onset of instability above the critical Reynolds number, evolve further with increasing Reynolds number. Jet detachments occur at sufficiently high Re. Onsets of TW-vortices and occurrence of jet detachments in the simulations agree very well with theoretical and experimental results.