Thermal self-propulsion of a photon torpedo

In this example we consider a warm asymmetric particle---a photon torpedo---in a cold environment. The thermal radiation from the particle carries away not only energy but also linear momentum, forcing the particle to recoil in the opposite direction by conservation of momentum. This is the phenomenon of thermal self-propulsion, and we will use buff-neq to predict the acceleration of a variety of torpedo designs in an effort to identify the maximally self-propelling configuration.