Direct numerical simulations of turbulent shear flows

This contribution is concerned with the simulation of turbulent shear flows. First, direct numerical simulations (DNS) are introduced, focusing on the challenges associated with computing turbulent flows without any empirical modelling. The numerical method of one of our DNS codes is presented in detail and its performance on different HPC systems is discussed, in particular issues arising with multi-core architectures. An overview of DNS-based research conducted in the Aerodynamics and Flight Mechanics Research group at the University of Southampton is then given, in an attempt to highlight how large-scale DNS performed on HPC resources can be used as a ‘virtual wind tunnel’, i.e. to conduct numerical experiments that cannot be performed in traditional laboratories. A range of different physical problems is discussed, including the noise generation of jets and turbulent flows over airfoils, turbulent structure generation in mixing layers and supersonic wakes, the sensitivity of turbulent spots to Mach number and wall temperature, turbulent breakdown of vortex rings, the influence of background turbulence on far-field wakes, and the evolution of wingtip vortice