Instantaneous velocity fields in the x-y plane of a zero pressure gradient turbulent boundary layer are measured using particle image velocimetry. It is found that there exist random, time-varying zones in the U-V fields in which the streamwise momentum is remarkably uniform. The largest dimension of a typical zone is proportional to the boundary layer thickness. The zone closest to the wall co...

Despite of a lot of efforts and interesting results, accretion disk theory is still under development and there are several unknowns: specifically, all available models are in the steady state approximation. In this letter, we investigate unsteady motion, beginning with shock wave–turbulence interaction. Indeed, unsteady flow allows this type of interaction, which in turn results in substantial...

Measurements have been made in the wake of a model wind turbine in both a weakly unstable and a baseline neutral atmospheric boundary layer, in the EnFlo stratified-flow wind tunnel, between 0.5 and 10 rotor diameters from the turbine, as part of an investigation of wakes in offshore winds. In the unstable case the velocity deficit decreases more rapidly than in the neutral case, largely becaus...

Direct numerical simulations (DNS) are conducted of flow through a linear low-pressure turbine cascade with T106 blade sections at Re=60,000, based on chord and isentropic exit velocity. A highly efficient in-house compressible Navier-Stokes solver was adapted for turbine cascade simulations and applied to investigate the effect of inflow disturbances on transition behaviour and blade profile l...

Preliminary results for a new flat plate test facility are presented here in the form of Computational Fluid Dynamics (CFD), flow visualisation, pressure measurements and thermal anemometry. The results from the CFD and flow visualisation show the effectiveness of the plate design, with the trailing edge flap anchoring the stagnation point on the working surface and reducing the extent of the l...

In the stably stratified interior of the ocean, mesoscale eddies transport materials by quasiadiabatic isopycnal stirring. Resolving or parameterizing these effects is important for modeling the oceanic general circulation and climate. Near the bottom and near the surface, however, microscale boundary-layer turbulence overcomes the adiabatic, isopycnal constraints for the mesoscale transport. I...

In this paper an experimental and theoretical investigation is presented on the role of large-scale coherent structures in the zeropressure-gradient turbulent boundary layer. Attention is given to the proposal by Adrian, Meinhart & Tomkins (2000) that hairpin vortices are organized into spatially correlated packets or trains of vortices which extend over many boundary layer thicknesses in the s...

This paper presents a numerical study of high wavenumber coherent structure evolution in boundary layer transition flow using recently-developed high order Combined compact difference schemes with non-uniform grids in the wall-normal direction for efficient simulation of such flows. The study focuses on a simulation of an Adverse-Pressure-Gradient (APG) boundary layer transition induced by broa...