SIMULATIONS OF STRUCTURE FORMATION IN THE UNIVERSE

Cosmic structure has formed as a result of gravitational amplification of primordial density fluctuations together with the action of other physical processes (adiabatic gas dynamics, radiative cooling, photoio nization and recombination, radiative transfer). These complex nonline ar processes, acting over a wide range of length scales (from kilopars ecs to tens of megaparsecs), make this a difficult problem for computa tion. During the last two decades, significant progress has been made in developing numerical methods and statistical tools for analyzing si mulations and data. Combined with observational advances, numerical si mulations have led to the demise of several formerly popular models an d to an improved understanding of galaxy clusters, quasistellar object (QSO) absorption line systems, and other phenomena. This review summa rizes these advances.