High-accuracy CFD results for laminar flow in a stirred tank agitated by three Rushton turbines are used as a starting point for an in-depth analysis of mixing. Asymptotic mixing performance is in®estigated as a function of the Reynolds number by means of Poincare sections, which re®eal large segregated regions with sizes and shapes that ®ary ́ greatly o®er a relati®ely small range of Reynolds n...

Ubiquitous porosity gradients have a potentially important effect on the mixing of particle-bound tracers, such as 210Pb Mass-depth coordinates cannot be used to deal with these effects if values of the traditional mixing coefficient, D,, are required. This paper compares and evaluates three different means of dealing directly with porosity gradients while modeling bioturbation, i.e. mean const...

Satellite altimetric observations of the ocean reveal surface pressure patterns in the core of the Antarctic Circumpolar Current (ACC) that propagate downstream (eastward) but slower than the mean surface current by about 25%. We argue that these observations are suggestive of baroclinically unstable waves that have a steering level at a depth of about 1 km. Detailed linear stability calculatio...

Temperature and salinity profiles obtained with expendable CTD probes throughout Drake Passage between February 2002 and July 2005 are analyzed to estimate turbulent diapycnal eddy diffusivities to a depth of 1000 m. Diffusivity values are inferred from density/temperature inversions and internal wave vertical strain. Both methods reveal the same pattern of spatial variability across Drake Pass...

The dynamical role of geothermal heating in abyssal circulation is reconsidered using three independent arguments. First, we show that a uniform geothermal heat flux close to the observed average (86.4mWm−2) supplies as much heat to near-bottom water as a diapycnal mixing rate of ∼10−4 m2 s−1 – the canonical value thought to be responsible for the magnitude of the present-day abyssal circulatio...

Combination frequencies are observed in the Fourier spectra of pulsating DA and DB white dwarfs. They appear at sums and differences of frequencies associated with the stellar gravity-modes. Brickhill (1992) proposed that the combination frequencies result from mixing of the eigenmode signals as the surface convection zone varying in depth when undergoing pulsation. This depth changes cause tim...