Generating high resolution DNS for LES comparisons.

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Direct numerical simulations (DNS) of turbulent flows provide one of the primary data sets for comparing new models for turbulence against. This is despite limitations in the types of flows that DNS can study at high Reynolds numbers. The limitation for incompressible flows is that for efficient solution of the Poisson equation for pressure, Fourier decomposition in two or three directions is traditionally required. This has meant that the only reliable high Reynolds number DNS available is either in fully periodic flows or flows with one simple direction such as plane channel flow. The focus of this studentship would be the generation of high Reynolds number DNS for more complicated geometries and comparisons with a variety of LES models for these flows.DNS calculations of flow over a backward facing step, a square duct andsmooth, irregular terrain would be done with a state-of-the-art efficient spectral element code. Validation will be done with a finite volume code, which will be used for most of our LES calculations. The LES comparisons will be to our new mixed nonlinear model and similar models such as the Met Office stochastic model.