Turbulent Combustion Modeling Advances, New Trends and Perspectives
Turbulent combustion sits at the interface of two important nonlinear, multiscale phenomena: chemistry and turbulence. Its study is extremely timely in view of the need to develop new combustion technologies in order to address challenges associated with
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Lattice Boltzmann Methods for Reactive and Other Flows Christos E. Frouzakis
Abstract The lattice Boltzmann method (LBM) is receiving increasing attention in recent years as an alternative approach for computational fluid dynamics. Through its kinetic theory origin, the method inherits the physically appealing particle picture that can be adapted to simulate multiscale and multiphysics systems with sizes ranging from the microscale (where the continuum hypothesis may break down) to macroscale applications. The method is characterized by its straightforward implementation in complex geometries and the fact that it involves only nearest neighbor interactions without global operations, making LBM algorithms ideally suited for parallelization. However, the method in general employs a larger number of degrees of freedom per grid point than classical CFD approaches, and parallel implementation may be essential in order to meet the higher memory requirements. In this chapter, an overview of the method and its applications is presented focusing on recent model developments for the description of the averaged macroscopic behavior of isothermal and non-isothermal, single- and multi-component and reactive flows.
19.1 Introduction The conventional approach for modeling most scientific and engineering flows is based on the continuum description of macroscopic behavior formulated as partial differential equations for a few fields (e.g. continuity and Navier-Stokes equations for the density and momentum, respectively, in the case of isothermal flows). A numerical technique (finite difference/volume/element, spectral or spectral element method) is then employed to obtain the discretized set of equations on a topologically connected mesh that can be solved numerically on the computer.
Christos E. Frouzakis Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, Zurich, Switzerland, e-mail: [email protected] T. Echekki, E. Mastorakos (eds.), Turbulent Combustion Modeling, Fluid Mechanics and Its Applications 95, DOI 10.1007/978-94-007-0412-1 19, © Springer Science+Business Media B.V. 2011
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Christos E. Frouzakis
Alternatively, since on the microscopic level fluids consist of discrete particles (atoms or molecules interacting via classical or quantum mechanics potentials and following the Newton equations of motion), one can opt for a description based on physical particles and obtain the evolution of macroscopic variables as collective averages over an enormous number of individual trajectories. Introduced about fifty years ago, molecular dynamics (MD) is probably the most widely used family of particle methods [2]. It provides the most detailed description by solving Newton’s equations of motion to track the position and velocity of each atom or molecule in the system. While MD yields the correct description of fluids on the microscopic as well as the hydrodynamic scales, the typical length and time scales that can be simulated in practice are of the order of a few tens o
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