Astronomy and Astrophysics

A parameter study is undertaken for steady symmetrical planar field-aligned MHD bow shock flows around a perfectly conducting cylinder.For sets of values of the inflow plasma β and Alfvénic Mach number (M A ) which allow for switch-on shocks, a numerical solution is obtained which exhibits a complex bow shock shape and topology with multiple shock fronts and a dimpled leading front.For parameter values outside the switch-on domain, a classical single-front bow shock flow is obtained.These results show that the β and M A parameter regime for which the complex bow shock topology occurs, corresponds closely to the parameter regime for which switch-on shocks are possible.The axi-symmetrical field-aligned bow shock flow over a perfectly conducting sphere is then calculated for one set of values for β and M A in the switch-on domain, resulting in a complex bow shock topology similar to the topology of the flow around a cylinder.These complex shock shapes and topologies may be encountered in low-β space plasmas.Fast coronal mass ejections moving away from the sun in the low-β inner corona may induce preceding shock fronts with upstream parameters in the switch-on domain.Planetary and cometary bow shocks may have upstream parameters in the switch-on domain when the impinging solar wind occasionally becomes low-β.The simulation results may be important for phenomena in the Earth's magnetosheath.

# Solar and Space Plasma Dynamics # Physics and Astronomy # Ionosphere and magnetosphere dynamics # Computational Fluid Dynamics and Aerodynamics # Engineering

S. Darbon, A. Zavagno, J. M. Perrin, et al. (1986). "Astronomy and Astrophysics". The Physics Teacher. https://doi.org/10.1119/1.2342053