Large-eddy simulation in hydraulics: Quo Vadis?

The method of large-eddy simulation (LES) is used increasingly to address research and engineering problems of modern hydraulics. LES simulates directly the large-scale motion of the flow and employs a model to account for the effects that small-scale turbulence imposes on large eddies. This paper summarizes recent hydraulic and hydro-environmental research in which LES has been used. It demonstrates a wide range of applicability of the method and highlights some important research contributions that have been made in studies of large-scale turbulence-dominated flows in which LES delivered accurate predictions. Despite its recent successes, LES is not yet considered to be a universal tool in hydraulics; it cannot (yet) simulate certain flows of hydraulic interest, either because of lack of adequate supergrid models to handle utterly complex flow physics or because current computing resources hinder its applicability to real-life flows at realistically high Reynolds numbers. The paper discusses the challenges and opportunities of the LES method in hydraulics that have to be addressed for LES to play a major role in hydraulic research in the near to medium future.