Hydrostatic equilibrium

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

The stabilizing effect of the temperature on buoyancy-driven fluids

Abstract: The Boussinesq system for buoyancy driven fluids couples the momentum equation forced by the buoyancy with the convection-diffusion equation for the temperature. One fundamental issue on the Boussinesq system is the stability problem on perturbations near the hydrostatic balance. This problem can be extremely difficult when the system lacks full dissipation. This paper solves the stability problem for a two-dimensional Boussinesq system with only vertical dissipation and horizontal thermal diffusion. We establish the stability for the nonlinear system and derive precise large-time behavior for the linearized system. The results presented in this paper reveal a remarkable phenomenon for buoyancy driven fluids. That is, the temperature actually smooths and stabilizes the fluids. If the temperature were not present, the fluid is governed by the 2D Navier-Stokes with only vertical dissipation and its stability remains open. It is the coupling and interaction between the temperature and the velocity in the Boussinesq system that makes the stability problem studied here possible. Mathematically the system can be reduced to degenerate and damped wave equations that fuel the stabilization.

Le role de la pression fluide dans les deformations tectoniques

Abstract: It has been shown by K. Hubbert and W. W. Rubey that fluid pressure may play an important role in tectonic deformation when it becomes greater than that required for hydrostatic equilibrium. When the impregnating fluid in rock is under such excess pressure, the conditions of solid friction are drastically altered. The limit is reached when fluid pressure becomes equal to lithostatic pressure; rocks could then be displaced freely with respect to one another. Rough calculations show that this limit need not be reached; all overthrusts, whether due to lateral pressure or flow, can take place easily if fluid pressure is 95-98 percent of lithostatic pressure. Possible mechanisms for producing excess pressure are discussed.

Fluid holding device

Abstract: PROBLEM TO BE SOLVED: To provide a fluid holding device (hydrostatic bearings and a hydrostatic guide) suppressing accuracy deterioration of a mobile body due to a disturbance load fluctuating at high speed. SOLUTION: The fluid holding device includes displacement sensors 9 and 10 for measuring relative displacement between a spindle 3 and the hydrostatic bearings 4 and 5 due to a disturbance force; and land feed means 7 and 8 for moving forward or backward a land section of a hydrostatic pocket. By moving forward or backward the land section according to the relative displacement between the spindle 3 and the hydrostatic bearings 4 and 5 due to the disturbance force, the relative displacement between the hydrostatic bearings 4 and 5 and the spindle 3 due to the disturbance force is suppressed, thereby suppressing the accuracy deterioration of the fluid holding device due to the disturbance force. COPYRIGHT: (C)2011,JPO&INPIT

An Impact of Hydrostatic Extraction Scheme on BMRC’s Global Spectral Model

Abstract: There are two important features in geophysical fluid dynamics. One is that the atmospheric and oceanic equations of motion include the Coriolis force; another is that they describe a stratified fluid. The hydrostatic extraction scheme, or standard stratification approximation, posed by Zeng (1979), reflects the second aspect of geophysical fluid dynamics. There exist two major advantages in this scheme; accurate computation of the pressure gradient force can be obtained over steep mountain slopes, and the accumulation error in vertical finite differencing can be reduced, especially near the tropopause.Chen et al (1987) introduced the hydrostatic extraction scheme into a global spectral model, which attained preliminary success at low resolution. Zhang and Sheng et al (1990) developed and improved the hydrostatic extraction scheme in a global spectral model, in which C0, the parameter that represents the stratification of the reference atmosphere, changes not only with height, but also with latitude. Th

Turbulent lubrication for hydrostatic thrust bearing with a circular recess.

Abstract: This paper is concerned with the characteristics of hydrostatic thrust bearings operating in the turbulent regime. Using the calculated results of the three-dimensional turbulent mean velocity between a rotating disk and a fixed wall as already proposed, the pressure distribution, the load capacity and the oil flow rate of the hydrostatic thrust bearing with a circular recess are presented. Comparing the calculated results with the experimental ones, it has been found that the characteristics of the above bearing are little influenced by the transition to turbulence of the lubricant flow in the recess, but that the transition in the land produces an extreme change to the bearing characteristics such as the load capacity and the lubricant flow rate.