ABSTRACT

As shown in the last chapter, spatial filtering/averaging introduces Subgrid-Scale (SGS) stresses τ ij

LES, representing the effects of the unresolved, small-scale turbulence on the resolved/ filtered motion. One way to account for this effect is through an explicit SGS model for τ ij

SGS. As the effect is mainly dissipative, i.e. to withdraw energy from the resolved motion, another approach is to account for it through numerical dissipation introduced by the solution procedure, and this is described briefly in Chapter 5 on Implicit Large-Eddy Simulation (ILES) methods. However, in hydraulic-flow calculations, the most common method is still the use of an explicit SGS model, and in this chapter the most widely used SGS models are introduced.