A class of unsteady free convection flows over a differentially cooled horizontal surface is considered. The cooling, specified in terms of an imposed negative buoyancy or buoyancy flux, varies laterally as a step function with a single step change. As thermal boundary layers develop on either side of the step change, an intrinsically unsteady, boundary-layer-like flow arises in the transition ...

Ceramic-based hollow spheres are considered a great driving force for many applications such as offshore buoyancy modules due to their large diameter to wall thickness ratio and uniform wall thickness geometric features. We have developed such thin-walled hollow spheres made of alumina using slip casting and sintering processes. A diameter as large as 50 mm with a wall thickness of 0.5-1.0 mm h...

Measurements of turbulent fluctuations of horizontal and vertical components of velocity, salinity and suspended particulate matter are presented. Turbulent Prandtl numbers are found to increase with stratification and to become larger than 1. Consequently, the vertical turbulent mass transport is suppressed by buoyancy forces, before the turbulent kinetic energy (TKE) and vertical turbulent mo...

Buoyancy is a de-stabilizing force for diving cormorants that forage at shallow depths. Having to counter this force increases the cost of transport underwater. Cormorants are known to be less buoyant than most water birds but are still highly buoyant (rho= approximately 0.8 kg m(-3)) due to their adaptations for aerial flight. Nevertheless, cormorants are known to dive at a wide range of depth...

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...

In a stratified rotating fluid, frictionally driven circulations couple with the buoyancy field over sloping topography. Analytical and numerical methods are used to quantify the impact of this coupling on the vertical circulation, spindown of geostrophic flows, and the formation of a shelfbreak jet. Over a stratified. slope, linear spindown of a geostrophic along-isobath flow induces cross-iso...

Turbulent plumes, which are seen in a wide number of industrial and natural flows, have been extensively studied; however, very little attention has been paid to plumes which have an internal mechanism for changing buoyancy. Such plumes arise in e.g. industrial chimneys, where species can react and change the density of the plume material. These plumes with chemical reaction are the focus of th...

Measurements of osmotic equilibrium of colloidal solutions, ranging from 170,000 to 20,000 in molecular weight, show that the negative buoyancy of the solute molecules is additive to the osmotic pressure. Seen together with earlier measurements of positive buoyancy of oil suspensions, these data confirm that the osmotic interaction between solute and solvent at equilibrium is purely a force-cou...