An Owner's Guide to Smoothed Particle Hydrodynamics

We present a practical guide to Smoothed Particle Hydrodynamics (\SPH) and its application to astrophysical problems. Although remarkably robust, \SPH\ must be used with care if the results are to be meaningful since the accuracy of \SPH\ is sensitive to the arrangement of the particles and the form of the smoothing kernel. In particular, the initial conditions for any \SPH\ simulation must consist of particles in dynamic equilibrium. We describe some of the numerical difficulties that may be encountered when using \SPH, and how these may be overcome. Through our experience in using \SPH\ code to model convective stars, galaxy clusters and large scale structure problems we have developed many diagnostic tests. We give these here as an aid to rapid identification of errors, together with a list of basic prerequisites for the most efficient implementation of \SPH.