Multidimensional reactive flow models

Interesting is the Multidimensional Reactive Flow model developed by Tarver et al. [5,103,104) it is based on the Non-Equilibrium Zeldovich-von Neuman-Dhring theory. This model starts from the primary chemical changes occurring in the adiabaticaUy compressed thin layer of molecules of the given EM and multiphonon up-pumping due to shock, but in the mathematical description it works with experimental data of thermal explosion of EM [5,103,104) it considers the induction period of initiation of detonation. However, the induction period of the EM decomposition in front of the detonation wave makes the front kinetically unstable and pulsating [101 ]. 

Mechanism reduction, nevertheless, may be necessary in some applications — for example, to model multidimensional reactive flows. Even the fastest computers today cannot handle such problems using detailed mechanisms in a reasonable time frame. It must be recognized, however, that models that utilize reduced mechanisms would have a far narrower range of applicability than the ones that use comprehensive reaction mechanisms. Furthermore, models that are based on reduced mechanisms cannot be expected to be valid outside the limits set in the mechanism reduction step. 

Analytically Reduced Mechanisms Some problems can be described by models that involve a full reaction mechanism in combination with simplied fluid dynamics. Other applications may involve laminar or turbulent multidimensional reactive flows. For problems that require a complex mathematical flow description (possibly CFD), the computational cost of using a full mechanism may be prohibitive. An alternative is to describe... 

Optimization of internal engine combustion in respect of fuel efficiency and pollutant minimization requires detailed insight in the microscopic processes in which complex chemical kinetics is coupled with transport phenomena. Due to the development of various pulsed high power laser sources, experimental possibilities have expanded quite dramatically in recent years. Laser spectroscopic techniques allow nonintrusive measurements with high temporal, spectral and spatial resolution. New in situ detection techniques with high sensitivity allow the measurement of multidimensional temperature and species distributions required for the validation of reactive flow modeling calculations. The validated models are then used to And optimal conditions for the various combustion parameters in order to reduce pollutant formation and fuel consumption. 

Despite its title, and although it contains discussion of relevant numerical techniques, this article is not a comprehensive survey of the numerical methods currently employed in detailed combustion modeling. For that, the reader is referred to the reviews by McDonald (1979) and Oran and Boris (1981). Rather, the aim here is to provide an introduction that will stimulate interest and guide the enthusiastic and persistent amateur. The discussion will center mainly about low-velocity, laminar, premixed flames, which form a substantial group of reactive flow systems with transport. Present computational capabilities virtually dictate that such systems be studied as quasi-one-dimensional flows. We also consider two-dimensional boundary layer flows, in which the variation of properties in the direction of flow is small compared with the variation in the cross-stream direction. The extension of the numerical methods to multidimensional flows is straightforward in principle, but implementation at acceptable cost is much more difficult. 

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