Numerical Simulation of Turbulent Flows*

Turbulent flows are ubiquitous in nature, affecting daily life from atmospheric dynamics to the mixing of fuel and oxidizer inside internal combustion engines, to the aerodynamics of modern aircraft. Multi-scale nature of turbulent flows creates challenges for numerical simulations. However, the exponential growth in computer power (about two orders of magnitude every 7 years) has enabled high fidelity numerical simulations of canonical turbulent flows at moderate Reynolds numbers possible. The data generated from such simulations are used to probe and gain insight into the physics of turbulent flows, and to conduct experiments of discovery not otherwise available in laboratory experiments. Results from recent numerical experiments that have shed light on the universality of the structure and dynamics of turbulence near solid boundaries will be presented.
Large eddy simulation (LES) wherein large scale motions are resolved and the effect of small scales are modeled, is being used more frequently and effectively for engineering analysis of complex flows. Significant advances have been made in the development of accurate and efficient numerical methods, subgrid scale models and data analysis tools for LES of geometrically complex multi-physics flows. Recent examples of applications of LES will be presented.