Large eddy simulation

Summary

Large eddy simulation, or LES, is a method for computing turbulent flows that resolves the large eddies and models the small ones. It applies a spatial low-pass filter to the Navier–Stokes equations and solves the filtered equations on a grid whose spacing is about the filter width. The effect of the unresolved scales enters through a subgrid-scale stress that must be modelled, often by an eddy viscosity. It sits between direct numerical simulation, which resolves all scales, and the Reynolds-averaged equations, which model all fluctuations.