The monograph is devoted to modern mathematical models and numerical
methods for solving gas- and ?uid-dynamic problems based on them. Two
interconnected mathematical models generalizing the Navier-Stokes system
are presented; they differ from the Navier-Stokes system by additional
dissipative terms with a small parameter as a coef?cient. The new models
are called the quasi-gas-dynamic and quasi-hydrodynamic equations. Based
on these equations, effective ?nite-difference algorithms for
calculating viscous nonstationary ?ows are constructed and examples of
numerical computations are presented. The universality, the ef?ciency,
and the exactness of the algorithms constructed are ensured by the
ful?llment of integral conservation laws and the theorem on entropy
balance for them. The book is a course of lectures and is intended for
scientists and engineers who deal with constructing numerical algorithms
and performing practical calculations of gas and ?uid ?ows and also for
students and postgraduate students who specialize in numerical gas and
?uid dynamics.