Large Eddy Simulation in Hydraulic Engineering: Examples of Laboratory-Scale Numerical Experiments

Abstract

Over the years, large eddy simulation (LES) has emerged as a tool to study problems in fluid mechanics characterized by complex physics and geometry. Among these, attention has been paid to studying problems of relevance in hydraulics and environmental fluid mechanics. For many years, LES has been used as an underresolved, or coarse, direct numerical simulation (DNS) where the scales unrepresented by the grid are modeled by means of a sub-grid-scale model, designed to drain energy from the resolved scales of motion. This method, although limited in applicability because of its computational cost, has allowed exploitation of the physics of a class of idealized flow fields of importance in hydraulic engineering. This study reports on investigations into processes of interest to hydraulic engineering. Some significant examples of such studies, together with relevant research from the literature, are given. Specifically, a description of literature related to turbulence in presence of longitudinal bars and local scours, studies of irregular roughness present in hydraulic applications, studies of Lagrangian and Eulerian dispersion processes, and studies of gravity currents is given. Although unable to give an answer to real-scale problems in hydraulic engineering, such studies allow unveiling of the physics behind phenomena present in hydraulics and, on the other hand, allow improved parametrization to be used in reduced-order models. The study is concluded with the author’s point of view on the importance of LES in hydraulic engineering in the upcoming future.