Hydrostatic equilibrium

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

Investigation of Interaction Between Oil Spills and Hydrostatic Changes

Abstract: In this paper an assessment of the potential oil outflow from tankers in the case of grounding is presented. The purpose of the study is to investigate how the introduction of double sides, double bottom and damage location will influence the amount of oil escaping from a damaged tank. Furthermore, the objective is to analyze the interaction between oil outflow and hydrostatic changes. In a previous paper, OMAE2008 [1], the pressure integration technique has been utilized to estimate the spill rate and the potential amount of spill without considering the hydrostatic changes. The results were confirmed by CFD simulations. The principles of this technique were presented and its advantages and disadvantages were discussed. In this paper interaction between oil leakage and hydrostatic changes is studied. In order to investigate possible additional oil spill caused by hydrostatic changes two procedures are utilized. In the first procedure, it is assumed that the oil flows out from the cargo tank or water flows in till hydrostatic equilibriums is attained, and subsequently the buoyancy changes due to oil outflow or water inflow are calculated. The additional oil spills caused by the hydrostatic changes are then calculated. The computations are carried out iteratively and continued until the difference between oil loss volumes obtained from two consecutive computations reaches a prescribed tolerance. In reality, there is no time lag between the buoyancy changes and oil loss volume. In order to eliminate the lag, time domain procedure has been applied. In the second procedure, the oil spill and hydrostatic changes are calculated simultaneously in each time step.Copyright © 2009 by ASME

The formation of prominences by thermal instability: A numerical study

Abstract: A two-dimensional model of prominence formation in a region containing a magnetic neutral sheet is constructed for a variety of initial conditions, assuming the coronal plasma to be described by the usual hydromagnetic approximation, with infinite electric conductivity. In each case the magnetic field is initially vertical, varying antisymmetrically with respect to the neutral sheet, to a maximum value at a distance of 70 000 km from the neutral sheet. In the first case, the plasma is initially in hydrostatic equilibrium, whereas in successive cases, the pressure is assumed to be of such a value that the plasma is in lateral equilibrium of total pressure (gas plus magnetic). In a variation of this case, the value of the solar gravitational field was artificially reduced, and the effects considered. Large lateral motions are produced in each case, thus apparently inhibiting the condensation of prominences, with the exception of the unrealistic case of artificially reduced gravity. The results suggest that consideration either of a third component of the magnetic field (horizontal and parallel to the neutral sheet), or a finite conductivity, allowing magnetic recombination across the neutral sheet, or both, would more realistically represent the problem and might thus show the development of prominences.

A Semi-Implicit Finite Difference Model for Three-Dimensional Tidal Circulation

Abstract: A semi-implicit finite difference formulation for the numerical solution of three-dimensional tidal circulation is presented. The governing equations are the three-dimensional Reynolds equations in which the pressure is assumed to be hydrostatic. A minimal degree of implicitness has been introduced in the finite difference formula so that in the absence of horizontal viscosity the resulting algorithm is unconditionally stable at a minimal computational cost. When only one vertical layer is specified this method reduces, as a particular case, to a semi-implicit scheme for the solutions of the corresponding two-dimensional shallow water equations. The resulting two- and three-dimensional algorithm is fast, accurate and mass conservative. This formulation includes the simulation of flooding and drying of tidal flats, and is fully vectorizable for an efficient implementation on modern vector computers.

Numerical modelling of the flow in the annular multi-recess hydrostatic thrust bearing using CFD methods

Abstract: The current research of hydrostatic bearings and hydrostatic slide-ways is far from being over. The topic is constantly evolving, creating new geometries of the sliding bearings, developing new types of friction materials and lubricants. The control elements of hydraulic mechanisms that serve to regulation of the hydrostatic bearings tipping are still in progress. Almost every application has different requirements for the bearings, whether in terms of loading capacity, speed rotation, and also the price. All these aspects should be included in the design of hydrostatic thrust bearings. Thanks to great advances in the development of computer technology and software for numerical modelling, we can simulate real movement of viscous fluids. To create a numerical model of hydrostatic thrust bearing, Ansys Fluent 14.0 software package has been applied. The article describes the basic methods of numerical modelling of the given problem and evaluates the pressure field and the loading capacity of annular multi-recess hydrostatic thrust bearing and its dependence on the change in static pressure.