Boundary Element Methods (BEM) are essential in contemporary numerical computations within applied and engineering sciences. They serve as effective tools for analyzing various physical phenomena that can be represented mathematically through partial differential equations, making them valuable for numerical studies across diverse applications.
Stochastic numerical methods play an important role in large scale computations in the applied sciences. The first goal of this book is to give a mathematical description of classical direct simulation Monte Carlo (DSMC) procedures for rarefied gases, using the theory of Markov processes as a unifying framework. The second goal is a systematic treatment of an extension of DSMC, called stochastic weighted particle method. This method includes several new features, which are introduced for the purpose of variance reduction (rare event simulation). Rigorous convergence results as well as detailed numerical studies are presented.