Atmospheric pressure observations from the Southern Hemisphere are used to estimate monthly and annually averaged indexes of the southern annular mode (SAM) back to 1884. This analysis groups all relevant observations in the following four regions: one for Antarctica and three in the subtropical zone. Continuous surface pressure observations are available at a number of locations in the subtrop...

Siphons have been used since ancient times, but exactly how they work is still a matter of debate. In order to elucidate the modus operandi of a siphon, a 1.5 m high siphon was set up in a hypobaric chamber to explore siphon behaviour in a low-pressure environment. When the pressure in the chamber was reduced to about 0.18 atmospheres, a curious waterfall-like feature appeared downstream from t...

This experimental study investigated the back pressure (P(back)) versus flow (U) relationship for 10 different tubes commonly used for semi-occluded vocal tract exercises, that is, eight straws of different lengths and diameters, a resonance tube, and a silicone tube similar to a Lax Vox tube. All tubes were assessed with the free end in air. The resonance tube and silicone tube were further as...

Circular simple shear extrusion process was introduced as a new geometry for simple shear extrusion technique to fabricate ultrafine-grained materials. Similar to the simple shear extrusion method, this process is also based on direct extrusion, and the samples deform in a simple shear manner. In this investigation, the simulations were carried out using the commercial finite element code ABAQU...

A transonic air stream flowing over a rectangular cavity or enclosure is unsteady. At certain flow conditions, large scale oscillations develop in the shear layer which, for an open cavity, spans across the whole enclosure. The convected shear layer instabilities interact with the cavity geometry, they generate resonance, and induce large amplitude wall pressure fluctuations, aerodynamic pressu...

 Understanding the flow behaviour in a gas well is crucial for future production strategies, obtaining bottomhole conditions from wellhead production data, analyzing production data and estimating reservoir properties. In this work, the pressure profile and flow regime are studied on four wells of a multi-well, multi-layer gas-condensate reservoir, producing at high rate. The wells are deviate...

In this paper, the lift-law method was applied to design the axial flow pump. Based on Reynolds time-averaged N-S equations and standard k turbulent model, three-dimensional air-water bubbly flow in an axial flow pump impeller was simulated. Under the condition of bubble void fraction of 5%, pressure and void fraction distributions were respectively obtained, movement of bubbles in the impeller...

Maximizing network throughput via back-pressure routing is the subject of a considerable body of literature. However, the associated optimal throughput guarantees come at the cost of excessively high delays. Though there exists some proposals in literature for improving the delay performance, the impact of these proposals on the delay performance is very little in loopy networks (i.e., networks...

Perfusion abnormalities in the pressure-overloaded hypertrophied left ventricle could result from an increase in minimum coronary resistance or an increase in effective back pressure due to increased extravascular compressive forces. Since the pressure-flow relation of the maximally vasodilated coronary bed allows dissociation of minimum resistance (inverse slope [1/alpha PF]) and back pressure...

We present the construction of a continuous, daily (09:00 UTC), station-based (Azores-Iceland) North Atlantic Oscillation (NAO) Index back to 1871 which is extended back to 1850 with additional daily mean data. The constructed index more than doubles the length of previously existing, widely available, daily NAO time series. The index is created using entirely observational sea-level pressure (...