The ZEUS code for astrophysical magnetohydrodynamics: new extensions and applications

A brief review of the numerical methods implemented in the widely used ZEUS code for astrophysical magnetohydrodynamics (MHD) is given. Extensions of the numerical methods to treat problems in nonideal MHD in a variety of regimes are discussed. In particular, methods for treating Ohmic dissipation, and methods for studying partially ionized plasmas in which the ion and neutral components are weakly coupled through a collisional drag term are considered. Recent application of the methods to the study of the dynamics of accretion disks is described.