Hydrostatic equilibrium

About: Hydrostatic equilibrium is a research topic. Over the lifetime, 2451 publications have been published within this topic receiving 62172 citations.

Gravitational wet-avalanche pressure on pylon-like structures

Abstract: Low-speed wet avalanches exert hydrostatic forces on structures that are flow-depth dependent. However, the pressure amplification experienced by smaller structures has not been quantified previously. In particular, recent wet avalanche pressure measurements, performed with small cells at the “Vallee de la Sionne” test site, indicate significantly higher pressures than those considered by engineering guidelines and common practice rules based only on the contribution of inertial forces. In order to gain a deeper understanding and investigate the relevance of these measurements for structural design, we analyzed data measured on obstacles of different shapes and dimensions. The pressure measured on a 1 m 2 pressure plate was, on average, 1.8 times smaller than the pressure measured on a 0.008 m 2 piezoelectric cell installed on a 0.60 m wide pylon and 2.9 times smaller than the pressure measured on a 0.0125 m 2 cantilever sensor extending freely into the avalanche flow. Further, avalanches characterized by a gravitational flow regime exerted pressures that increased linearly with avalanche depth. For Froude numbers larger than 1, an additional square-velocity dependent contribution could not be neglected. The pressure variations encountered by the different obstacles could be explained quantitatively with a granular force model, that assumes the formation of a mobilized volume of snow granules extending from the obstacle upstream whose dimensions depend on the incoming flow depth and the obstacle width. This mobilized volume is associated with the formation of a network of gravity-loaded grain-grain contacts, also called granular force chains, which densifies in front of the obstacle, producing force amplification. Our results underscore the fundamental influence of the dimensions of both the sensor and the obstacle on pressures in the gravitational flow regime and may help to improve rules for structural design.

Spherically symmetric model atmospheres using approximate lambda operators - IV. Computational details of the thermal balance method

Abstract: The condition of a thermal balance of electrons is used in a linearization method of calculation of spherically symmetric NLTE model atmospheres in hydrostatic and radiative equilibrium Computational details of the method are presented and discussed The method is shown to be robust and powerful It is superior to the commonly used method based on the condition of radiative equilibrium

Hydrostatic transmission lubrication

Abstract: A hydrostatic transmission having a pump and a motor of the radial piston type with each cylinder slipper bearing rotatably supported by a hybrid or combination hydrostatic and hydrodynamic bearing on an internal bearing. The hydrostatic bearing component has a restricted port connecting hydrostatic pressure fluid from the cylinder to supply a distribution recess in the slipper bearing surface for hydrostatic pressure feed of the fluid film providing hydrostatic balancing pressure gradient between the slipper and internal bearing to balance a high percentage of the hydrostatic pressure load and to meet flow requirements for low speed operation. The hydrodynamic bearing component has a low pressure source to spray fluid on the internal bearing, annular dams on each side retaining fluid on the internal bearing, and a taper at the leading edge of the slipper bearing to force fluid into the bearing clearance and provide a hydrodynamic balancing pressure component and fluid flow increasing with speed to balance the centrifugal load and effect balancing of the remaining hydrostatic load and to meet flow requirements which increase with speed. The total hydrostatic and hydrodynamic balancing pressure balances the total load.