Although the application boundary element method (BEM) has a long history in computational fluid dynamics which dates back to the late 1950s and early 1960s, its developments as a problem-solving tool for general problems of fluid dynamics did not start until recently. Taking as its theme time dependent and time-harmonic problems in engineering, this volume demonstrates that boundary element methods are both elegant and efficient in their application to such problems and therefore worthy of considerable development. The text contains a collection of reviews comprising state-of-the-art applications of BEM to nonlinear problems. Subjects covered include: Helmholtz and Poincare potential-vorticity decompositions for the analysis of unsteady compressible viscous flows; advanced boundary element methods for steady incompressible thermoviscous flow; a time-dependent incompressible viscous BEM for moderate Reynolds numbers; a boundary integral formulation in primitive variables for unsteady viscous flows; Newtonian and non-Newtonian unsteady flow problems; a general theory of unsteady compressible potential flows with applications to airplanes and rotors; recent advances in solution metho