Large-eddy simulation of controlled and uncontrolled turbulent boundary layers

This article presents a comparison of the implicit (no model) large-eddy simulation (LES) technique and the local integral length-scale approximation (ILSA) sub lter model. The focus is on the numerical simulation of at plate turbulent boundary layers and active ow control using synthetic jets. After initial veri cation of the simulation setup, comparative studies are presented to investigate the dependence on spatial and temporal resolution, the level of arti cial dissipation, and some additional simulation parameters. Overall the ILSA model produces slightly more consistent and accurate results than the implicit LES approach. It also reduces computational cost by reducing the number of linear iterations required at each stage of the time-marching method. The controlled results generated by the implicit LES are in reasonably good agreement with experiment and give additional details of the spatial change in time-average skin friction. However, more work is needed to e ciently apply the ILSA model to the controlled case. Instabilities originating in the slot of the jet limited the ILSA model to a time step size one to two orders of magnitude smaller than the implicit LES approach.