Advances in the visualization and prediction of turbulence are shedding new light on mass transfer in the turbulent boundary layer. These discoveries have important implications for many topics in environmental science and engineering, from the transport of earth-warming CO2 across the sea-air interface, to nutrient processing and sediment erosion in rivers, lakes, and the ocean, to pollutant r...

The article presents the main conclusions obtained in special issue “Atmospheric Boundary Layer and Free Atmosphere: Dynamics, Physical Processes, Measuring Methods”. average meteorological quantities as well turbulent characteristics different atmospheric conditions are considered.

We investigate the early stages of mass convection in a colloidal suspension at high solutal Rayleigh number Ras. From the time evolution of shadowgraph images and by assuming a diffusive growth of the boundary layers we obtain an indirect measurement of the concentration boundary layer thickness delta* at the onset of convection. We show that the dimensionless boundary layer thickness delta=de...

Here we describe the application of a multiple camera planar particle image velocimetry (PIV) measurement to achieve a large field of view (FOV) in a high Reynolds number turbulent boundary layer. Measurements are performed over a FOV of 0.8m × 0.5m (2.25δ × 1.4δ, where δ denotes the boundary layer thickness) in the streamwise and wall-normal directions respectively in a turbulent boundary laye...

The behaviour of the steady, horizontally homogeneous, neutral, barotropic planetary boundary layer (PBL) has recently been examined by Garratt and Hess. In Garratt and Hess (2002) modelled profiles of the mean wind, the geostrophic departure and turbulent stress components were compared with observations; in Hess and Garratt (2002 a,b) predicted integral measures, such as the geostrophic drag ...

The relaxation of a shear flow (the process of an equilibrium state recovery) caused by the presence of a disturbance source such as a wall fence, roughness elements or obstacle in a turbulent boundary layer is a slow process which can not be predicted, at least accurately, even on the basis of current turbulence models. Previous investigations [1 – 3] are devoted to the study of the process of...

Shear and buoyancy are both known to contribute to the development of boundary layers, whose characteristics include turbulent mixing of scalar quantities within the layer. Purely shear-driven boundary layers include airflow over an airplane wing and stream flow over a bottom surface. Buoyancy-driven boundary layers include the atmospheric convective boundary layer (CBL) and the upper levels of...

On bou *A According to Lighthill (1995), Prandtl’s (1904) boundary layer has had the same transforming effect on fluid dynamics as Einstein’s 1905 discoveries had on other parts of physics, which, by the way, were celebrated in 2005 as the World Year of Physics. That the boundary layer becomes turbulent was formally known to Blasius (1908), though, of course, the origin of turbulence in a pipe ...