Physical Oceanography of the North Polar Sea

General account of the 20th century results of observations on bathymetry, ocean currents, temperature and salinity of the Arctic Basin. Bibliography (10 items)

High performance simulations of yield stress fluids in a structured adaptive mesh refinement framework with embedded boundaries

Viscoplastic fluids are a class of non-Newtonian liquids characterised by their yield stress. Unless an external stress is applied which is larger than this threshold value, the fluid does not flow, but exhibits rigid body behaviour. Above the yield stress, applied forces cause viscous deformation. Such fluids play important roles in a range of fields, notably in wellbore drilling, which is the application that motivated this project. One aspect of this operation requires displacement of drilling fluid by cement in the annulus between casing and geological surroundings, and both of these fluids are viscoplastics. Ensuring that this is done properly is of utmost importance to the overall safety of the drilling operation. Often, numerical simulations are the only viable way of experimenting with the effect of drilling parameters and fluid properties on the flow configuration and resulting behaviour. Unfortunately, the presence of a yield stress leads to a singularity in the apparent viscosity at zero strain. This causes substantial computational expense for the algorithms used to simulate fluid flow numerically, even when regularisation techniques are employed to alleviate the problem. Consequently, most published results in the literature on computational viscoplasticity has been restricted to two-dimensional and steady-state flows. In an attempt to address this, we have applied state-of-the-art techniques from high-performance computational fluid dynamics to the viscoplastic flow problem. Specifically, we utilise spatio-temporal adaptive mesh refinement on structured meshes in this context for the first time. This is achieved through the software framework AMReX, which includes state-of-the-art numerical tools for solving partial differential equations with optimal parallel scaling. The ability to rapidly simulate unsteady viscoplastic flow problems in three dimensions is demonstrated by novel numerical experiments in a lid-driven cavity. In order to investigate flows in more interesting domain geometries and around objects, an embedded boundary algorithm has been developed which works alongside the viscoplastic flow solver. We show how this methodology can be utilised to simulate flow inside non-rectangular objects, and investigate fully three-dimensional viscoplastic flow past several shapes of bodies for the first time.EPSRC Centre for Doctoral Training in Computational Methods for Materials Science grant number EP/L015552/1 BP International Centre for Advanced Materials (BP-ICAM) Extra support towards living expenses through the Aker Scholarshi

Lateral mixing in the deep water of the South Atlantic Ocean

The deep-sea circulation of the Atlantic has recently been carefully analyzed by Wiist (1935) who, on the basis of the tongue-like distribution of temperature and salinity, has drawn conclusions as to the direction of flow at different depths. He considers that an exchange of deep :water between the North Atlantic Ocean and the Antarctic Ocean is maintained by a flow to the north along the bottom of Antarctic water and a flow to the south at lesser depths of North Atlantic deep water and Mediterranean water

Roald Amundsen

Contains a biography of the Norwegian explorer, 1872-1928, who was the first to navigate the Northwest Passage and to fly across the Arctic Ocean. His early life, travels in the Antarctic, and financial difficulties are described; his arctic explorations are recounted: through the Northwest Passage on the Gjoa 1903-1906, and the Northeast Passage on the Maud 1918-25, the scientific data accumulated; the north magnetic pole relocated by the Gjoa party. The Amundsen-Ellsworth flight of 1925 and that of Amundsen-Ellsworth-Nobile in 1926 pioneered the use of aircraft in arctic exploration

Colonization of experimentally arranged resource patches - a case study of fungivorous beetles

The study focuses on a colonization experiment of beetles, using sporocarps of tinder fungus Fomes fomentarius. Initially, a mapping of all sporocarps of F. fomentarius and its inhabitants was made in a 225 ha area of boreal forest in southern Norway (control dataset). 62% of the sporocarps contained one or more beetle individuals. Experimental sporocarps were then placed out for three years, collected and dissected. 21% of these were colonized. The comparison between control and experiment showed that species assemblages were rather similar. Successful between-tree colonization and reproduction in experimental sporocarps by the darkling beetle Bolitophagus reticulatus was observed. Cis jacquemartii colonized 14% of the experimental sporocarps, and there was no effect of distance from known dispersal sources on colonization for this species. This indicates that C. jacquemartii was well able to locate and colonize new substrate within the scale covered in the study

Note on the correlation of reversing thermometers

Corrections have to be applied to the readings of protected and unprotected reversing thermometers because they are read at a temperature that differs from that at the time of reversal. In deriving these corrections it is generally assumed that Feruglio\u27s (1912) equation [(5) below] is exact. It is shown here that Feruglio\u27s equation is not quite exact, but a close approximation. From this equation practical formulae, equations (6) and (8) below, can be derived very simply without further sacrifice of accuracy

On the annual and diurnal variation of the evaporation from the oceans

The average annual evaporation of the oceans in different latitudes can be considered fairly well established (Mosby, 1936, Wtist, 1936), but so far little is known as to the character of the annual and the diurnal variations. Helland-Hansen (1930) has pointed out that evaporation will be facilitated if the sea surface is warmer than the air, whereas evaporation will decrease or cease if the sea surface is colder...

O\u27Brien v. Great No. Ry., 400 P.2d 634 (Mont. 1965)

O\u27Brien v. Great No. Ry