Eddy Collision Models for Turbulence

Simple fluids such as gases and liquids are the result of collisions between molecules. More complex fluids, such as granular flows and colloidal suspensions (non-Newtonian fluids), result from the more complex collision (or interaction) behaviors of their constituent particles. In this paper it is demonstrated that collision rules can be constructed for large chunks of fluid material (eddies) such that the resulting collective system behaves like the mean (RANS) flow of a turbulent fluid. The collision model approach has a number of advantages over classic Reynolds stress transport (RST) models. For example, turbulent transport does not require a model and mathematical constraints like realizability are automatically satisfied. Using some ideas from lattice-Boltzmann methods and adaptive moving mesh algorithms for CFD it is shown that this modeling approach can be made computationally efficient and comparable in cost to classic Reynolds stress transport (RST) models. Finally, it is shown that the collisional approach to turbulence modeling can lead to some insights into turbulence and turbulence modeling that would probably not have been achieved via the traditional RST approach.