Three‐dimensional Magnetohydrodynamic Numerical Simulations of Cloud‐Wind Interactions

Abstract

We present results from three-dimensional numerical simulations investigating the magnetohydrodynamics of cloud-wind interactions.The initial cloud is spherical, while the magnetic eld is uniform and transverse to the cloud motion.A simplied analytical model that describes the magnetic energy evolution in front of the cloud is developed and compared with simulation results.In addition, it is found that the interaction of the cloud with a magnetized interstellar medium results in the formation of a highly structured magnetotail.The magnetic ux in the wake of the cloud organizes into ux ropes, and a reconnection current sheet is developed as eld lines of opposite polarity are brought close together near the symmetry axis.At the same time magnetic pressure is strongly enhanced at the leading edge of the cloud from the stretching of the eld lines that occurs there.This has an important dynamical e ect on the subsequent evolution of the cloud, since some unstable modes tend to be strongly enhanced.