Turbulence: Numerical Flow Simulation

This lecture delves into the challenging topic of turbulence, exploring its wide range of length and time scales, extreme sensitivity, and analytical limitations. It covers simple turbulent flows like free turbulent flows and wall-bounded flows, discussing mean flow, turbulent structures, and turbulence anisotropy. The lecture also explains numerical flow simulation methods, including Direct Numerical Simulation (DNS), Large-Eddy Simulation (LES), and Reynolds-averaged Navier-Stokes (RANS) equations with turbulence models. It details the filtering operations and closure models in LES, the resolution of all scales in DNS, and the Reynolds stress tensor in RANS equations. The challenges and methods of simulating turbulent flows are analyzed, highlighting the trade-offs between accuracy and computational cost.