Analysis of length scales in open channel flow for inlet definition of LES of tidal stream turbines

The tidal streams considered for energy extraction are known to include strongly sheared velocity profiles and large variation of flow speed due to both waves and eddies. One approach for analysing turbine loading, due to such tidal flows, is eddy-resolved computational fluid dynamics. A key issue with eddy-resolved methods is the specification and generation of an inflow that represents the turbulence characteristics and flow-profile of a full-scale site. This paper addresses Large Eddy Simulation (LES) of both fully developed and developing open channel flow with the aim to evaluate turbulent length scales to compare with physical measurements from both lab and field scale data.