The motion of wind-driven shells

We present a method for solving problems in which a stellar wind interacts with the surrounding environment through the production of a 'double radiative shock' structure. This condition is generally met in problems involving winds ejected from young stars. We describe a method that can be applied to problems of winds with arbitrary time and angular dependence, interacting with a stationary environment with an arbitrary density distribution. We apply the method to the interaction of: a steady wind (with an instantaneous 'turning-on') with a power-law environmental density stratification, a 'wind plus jet' ejection with a toroidal environmental density stratification, and to the interaction of an isotropic wind with a clumpy environment. These three examples illustrate the wide range of possible applications of the proposed method. We also show a comparison between some of our thin-shell solutions and three-dimensional isothermal gasdynamic simulations of the flows. These comparisons are used as an evaluation of the applicability of our thin-shell solutions to the real flows.