Hybrid continuum-particle methods

In this article, we begin by reviewing the variety of problems associated with laboratory and flight investigations of hypersonic rarefied flows. Then a complete review of computational methodologies is provided. This includes both continuum and particle methods. The focus is on particle methods and details are provided on general concepts. Then, several of the most commonly employed chemistry models are described in detail. There are two components to any chemistry model the rate of chemical reaction, and the mechanics of chemical reaction. These are discussed separately. Models for gas-surface interaction and hybrid methods that use both continuum and particle descriptions of the gas flow are also briefly reviewed. Results are reviewed for hypersonic conditions in air applicable to the Space Shuttle and to ballistic missiles where both dissociation and exchange reactions are important. The behavior of rarefled flow chemistry models is first considered in a test cell environment. Then, the models are applied to... 

In the absence of any significant body of experimental data for rarefied, hypersonic flows, vehicle design has depended greatly on computational modeling. In this section, we briefly review continuum approaches for computing rarefied gas flows. We then pass on to a more complete description of the methods and models associated with a particle formulation. Hybrid methods that combine continuum and particle methods are reviewed briefly. 

In essence, CPMD is a fairly typical example of the hierar-chy-of-models approach in which the electrons are treated quantum-mechanically as a massless fluid while nuclei are described as a set of classical particles. A wide scope for the application of hybrid simulations is provided by problems in polymer science. There are hybrid methods coupling a classical molecular-dynamics model with an elastic continuum modd, " RISM theory," " " and so on. The... 

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