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Activity title

Non-Equilibrium Turbulent Boundary Layers in High Reynolds Number Flow at Incompressible Conditions

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Applied Vehicle Technology

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Pressure Gradient, Roughness, ThreeDimensionality, Turbulent Boundary Layer


Ever improved fluid dynamics modelling and simulation tools are in constant demand in the naval sea and aviation communities, driven both by need and the advance of computer technology. Accurate prediction of boundary layers is a fundamental pre-requisite of successful vehicle design and operation in terms of drag, manoeuvring and acoustic signature. Over the years the focus of incompressible boundary layer research has been, perhaps disproportionately, on low Reynolds numbers and idealized conditions. In the STO community there has been a heavy emphasis on compressible boundary layers and high-speed flow related non-equilibrium problems. Comparatively little attention has been paid to non-equilibrium boundary layers at conditions relevant to most naval vehicles. The focus of this ET will be on boundary layers at realistic conditions where the Reynolds number is very large and the boundary layer grows on surfaces including roughness, curvature and three-dimensionality with regions of increasing and/or decreasing pressure. This request is driven by current research progress in NATO countries driven by technological developments and relevant research programs, and the desire to amplify and accelerate that progress via international collaboration.


The objective of this ET is to examine and develop opportunities for collaboration between NATO researchers in the area of non-equilibrium turbulent boundary layers in high Reynolds number flows at incompressible conditions. The deliverable of the ET will be a proposal for a following workshop (RSW) or specialists’ (RSM) meeting.


1. High Reynolds number boundary layers at incompressible Mach numbers and vehicle relevant conditions including, specifically • Effects of surface roughness • Effects of surface curvature • Effects of favourable and adverse pressure gradient • Effects of three-dimensionality 2. Experimental and computational studies of such flows with a view to the development of • Improved turbulence models for RANS methods • Improved wall models for LES, DES and other simulation approaches • Improved low order prediction methods suitable for design and control • Improved physical understanding and the development of scalings and correlations

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