Synthetic turbulence inflow conditions for large-eddy simulation

Direct numerical or large-eddy simulations of the majority of spatially inhomogeneous turbulent flows require turbulent inflow boundary conditions. A potential implication is that any results computed may be strongly influenced by the prescribed instantaneous inlet velocity profiles. Such profiles are practically never available, and a usual practice is to generate synthetic inflow data satisfying certain statistical properties, which may, for example, be known from experimental data or empirical correlations. The present paper describes a new method for generating turbulent inflow data based on digital filters that is capable of reproducing specified statistical data. Two variants of the approach are presented: a simple method in which the Reynolds stresses and a single length scale are prescribed, and a more detailed approach that is able to reproduce the complete Reynolds-stress tensor as well as any given, locally defined, spatial and temporal correlation functions. The application of the methods to a plane jet flow and to a developing wall boundary layer serve to demonstrate the applicability of the approach.