Lagrangian Studies of Turbulent Mixing and Dispersion Using High-Resolution Computations

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ABSTRACT Proposal Number: CTS-9705678 Principal Investigator: Yeung The objectives of this project are to study fundamental aspects of enhanced mixing and dispersion in turbulent flows. It is widely recognized that the modeling of molecular mixing is a problematic area in probability-density-function methods which otherwise hold great advantages for reacting flows, and in Lagrangian stochastic models that are used to predict pollutant dispersion in the atmosphere. The approach is to use direct numerical simulations based on exact transport equations to extract Lagrangian statistics of single and multiple passive scalars (such as chemical species or contaminants) and molecular displacements, and to compare model predictions directly with the simulation results. The data to be examined are novel to the literature, and virtually beyond experimental measurement. The latest advances in massively parallel computing will be exploited to provide high-resolution simulation data over a range of Reynolds and Schmidt numbers, which would allow a careful study of issues of similarity scaling important to the fundamental description of scalar transport in turbulence.