The transitional boundary layer flow over a flat plate is investigated. The boundary layer flow is known to develop unstable Tollmien-Schlichting waves above a critical value of the Reynolds number. However, it is also known that this transition can be observed for sub-critical Reynolds numbers. In that case the basin of attraction of the laminar state coexists with the sustained turbulence. In...

Grazing flow passing over the quiescent fluid inside the cavity of a Helmholtz resonator can excite the resonator. When the frequency of the instabilities within the shear layer is near the natural frequency of the resonator then flow-excited resonance will occur. This process causes self-sustained periodic oscillations of the flow over the orifice of the resonator. Quantitative numerical predi...

Direct numerical simulation of turbulent homogeneous shear ow is performed in order to clarify compressibility e ects on the turbulence growth in the ow. The two Mach numbers relevant to homogeneous shear ow are the turbulent Mach number Mt and the gradient Mach number Mg . Two series of simulations are performed where the initial values of Mg and Mt are increased separately. The growth rate of...

Sea ice is in almost constant motion in response to wind, ocean currents, and forces transmitted within the ice cover itself, thus there is nearly always a zone of sheared Sow between the ice and underlying, undisturbed ocean where turbulence transports momentum, heat, salt, and other contaminants vertically. The zone in which these turbulent Suxes occur, which can span from a few to hundreds o...

tion models, in spite of some advances, the boundary layer is still not represented realistically. Figure 1 illustrates an aspect of this problem by showing the opposing response of boundary layer (low) clouds to perturbation experiments (e.g., double CO2) in current climate models. The general problem of parameterization in fluids dates back to the first modern studies of turbulence during the...

The paper deals with separation of a nominally steady and two-dimensional incompressible boundary layer from the smooth surface of a rigid blunt body in the presence of a front stagnation point, here denoted by PF . In agreement with earlier studies on the flow past a bluff body, it is argued that in the limit of vanishing viscosity, i.e. in the limit where the globally defined Reynolds number ...

Laminar-turbulent breakdown in a swept-wing boundary layer is typically caused by secondary instabilities of steady crossflow vortices (CFVs). So far, boundary-layer suction for laminar flow control in three-dimensional boundary layers has been applied to reduce the crossflow and thus the growth of the primary vortices only. We investigate the influence of strong, localized suction (pinpoint su...

Results of recent experimental measurements of the effect of passive boundary layer flow control method using Large-Eddy Break-Up devices on aero-optical distortions caused by turbulent subsonic boundary layers at a range of trans-sonic speeds are presented. Measurements were performed using a Malley probe to collect instantaneous onedimensional wavefronts with high resolution. Detailed statist...

A combined experimental and numerical study of the boundary layer in a 4:1 aspect-ratio Rayleigh-Bénard cell over a four-decade range of Rayleigh numbers has been undertaken aimed at gaining a better insight into the character of the boundary layers. The experiments involved the simultaneous laser Doppler anemometry measurements of fluid velocity at two locations, i.e., in the boundary layer an...