Keynote Lecturer July 4, 2023, 9:10-10:00AM
Professor of Aerospace Engineering
University of Southampton,
Neil Sandham has been Professor of Aerospace Engineering at the University of Southampton since 1999. His area of expertise is direct and large-eddy simulation of transitional and turbulent flows over the full range of speeds from incompressible to hypersonic. He was the founding principal investigator of the UK Turbulence Consortium, exploiting high
performance computers for turbulent flow research. His current research projects include numerical simulation of rough surface flows and high-speed flow applications of exascale computing.
Unsteadiness of shock-wave/boundary-layer interactions in transonic and supersonic flows
Unsteadiness is a common feature of shock-wave/boundary-layer interactions. When separation is present, the separated shear layer is unstable, leading to highly energetic flow features. In addition, broadband unsteadiness is commonly observed at an order of magnitude smaller frequency compared to the shear layer structures. In such situations, for example in ramp or shock impingement configurations, there is usually a closed separation bubble, which is observed to ‘breathe’ at this low frequency, increasing and decreasing in size as the separation shock wave moves upstream and downstream. Multiple physical phenomena are present in these flows and some aspects may be by-products of the unsteadiness, rather than the fundamental cause. In this contribution, we will consider shock-related separation problems in a number of different configurations and extract some of the common features, as well as noting where there are significant differences between configurations. We consider upstream influences, in cases with an upstream turbulent boundary layer, as well as downstream influences in cases with laminar turbulent transition cases and in shock trains. We conclude by pointing to some differences between shock-impingement in supersonic flows and transonic buffet, where global modes appear to coexist with local separation bubble modes.