Reduced-basis modeling of turbulent plane channel flow

Very-large-eddy simulations of turbulent plane channel flow of various Reynolds numbers have been performed. The simulations are based on relatively small sets of modes from a proper orthogonal decomposition (POD) of a direct numerical simulation or large-eddy simulation of the same flow. The intention is to investigate how these reduced basis simulations respond to change in Reynolds number and geometry. We find that the dynamical systems are able to reproduce the mean velocity and Reynolds stress profiles as long as the aspect ratio of the channel or the Reynolds number does not increase or decrease from the original setting with more than 50% or 30%, respectively. When the objective is a coarse description of the flow dynamics, significant savings in terms of computational cost are achieved by deriving the dynamical systems from the POD-basis. One possible application of such reduced basis simulations can be to efficiently generate turbulent inlet boundary conditions for direct numerical simulations.