The aim of this Dstl-funded project (Dstl – 20200512) is to build a simulation database of compressible channel flow over several irregular rough surfaces for a range of friction Reynolds and Mach number. The goal is to understand how roughness influences the flow topology and key surface parameters such as heat flux and wall shear stress.
Currently, Direct Numerical Simulation (DNS) and experimental studies of rough wall flows are mostly limited to the incompressible flow regime. The limited data for high speed flows has resulted in most models being developed for RANS computation to be based on results from incompressible studies. There is evidence to suggest that compressibility effects can be important. For example, experimental investigations have shown that shock and expansion waves, which span the boundary layer, can be produced by a rough surface in supersonic flow. Furthermore, only a relatively small number of experimental and DNS studies have investigated the heat transfer effects due to roughness. Some existing experimental and DNS studies have suggested that using the Reynold’s analogy to calculate heat transfer may not give accurate results for rough surfaces.
In light of these issues, there is a need to increase the understanding of the effects of roughness on high speed boundary layers, so that models can be tested and developed. This research will investigate, through the use of DNS, to assess the influence of roughness on the skin friction, heat transfer and flow topology in compressible, non-adiabatic flow.
