Showing papers on "Hydrostatic equilibrium published in 1972"

Topological dissipation and the small-scale fields in turbulent gases.

Abstract: It is shown that a large-scale magnetic field possesses a hydrostatic equilibrium only if the pattern of small-scale variations is uniform along the large-scale field. Thus equilibrium obtains only if the variations in the field consist of simple twisting of the lines, with the twists extending uniformly the full length of the field. Any more complicated topology, such as two or more flux tubes wrapped around each other to form a rope, or braided or knotted flux tubes, is without equilibrium, no matter what fluid pressures are applied along the individual lines of force. The result is rapid dissipation and field-line merging, which quickly reduces the topology to the simple equilibrium form. The effect explains the absence of strong small-scale fields in the solar photosphere and in interstellar space in spite of the vigorous turbulence.

The Field Distributions and Balances in a Baroclinic Annulus Wave

Abstract: The detailed structure of a steady wave occurring in a rotating annulus of square cross-section and having a free surface is presented. The field distributions are obtained by numerical integration of the three-dimensional nonlinear Navier-Stokes equations. The distributions of pressure, temperature, and the three velocity components are displayed for the total fields and for the fields of deviation from the zonal means. Their dynamical balances are also discussed. The deviation wave is a type of Eady wave and the solution is used to discuss the structure of such waves in finite amplitude steady-state form under the influence of variations in baroclinicity, shear, and boundary layers. The side layers make little contribution to the characteristics of the wave in the deviation field although significant Ekman layer features do appear. The flow is essentially in hydrostatic and geostrophic balance except in the boundary layers. Heat conduction is important only in the side layers.

A Statistical Mechanical Approach to the Problem of a Fluid in an External Field

Abstract: A rigorous, equilibrium statistical mechanical treatment of a fluid in a weak external field is given. The technique involves a cell division which leads to upper and lower bounds for the free energy density. Under a suitable double limiting procedure these limits coalesce, yielding a free energy consisting of a field‐free term plus a field‐dependent term. The cell division allows a direct physical definition of the local pressure p(s) and the local density ρ(s). This treatment provides a rigorous derivation of the thermodynamics of a fluid in a weak external field and, in particular, the hydrostatic equation gradp = − ρ gradφ.

Pressure distribution in hydrostatic extrusion dies

Abstract: To be able to understand the detailed mechanics of plastic flow and lubrication during hydrostatic extrusion it is very desirable to be able to measure the precise pressure distribution along the length of the die.In the present work, experiments have been developed which enable this pressure distribution to be measured indirectly with reasonable accuracy and comparison is made between the distribution obtained experimentally during slow-speed hydrostatic extrusion of annealed copper and the distribution predicted by theoretical analysis. Very good agreement was obtained for the single geometry investigated.

Hydrostatic bearing systems

Abstract: Hydrostatic bearing systems comprising a shaft with a cylindrical pressure plate thereon supported by at least one hydrostatic bearing to make the shaft rotatable along its axis and displaceable along its axis by applying hydrostatic pressure to the cylindrical pressure plate.

Planetary structures in general relativity

Abstract: For a static single-zone planet assuming that 1) the pressure and density are connected by the equationP =K Q 1+1/n–s, 2) a complete spherical symmetry is preserved and the system is in hydrostatic equilibrium; in section II, the expressions for the field equations have been obtained in suitable dimensionless forms. In section III the solution of the field equations forn=0 (which represents a homogeneous liquid) has been given in explicit form; for other prescribed value ofn=2/5 it has been pointed out that solutions must be performed by numerical integrations. Expressions for the mass-radius relation, the ratio of central to average density, the total energy, the proper energy and gravitational potential energy, which give some informations about the internal structure of the planet, have also been given in this section. Section IV discusses the velocity of sound at the centre of the planet. A few concluding remarks regarding the structure of the planet have been given in section V.

Pressure Cell with Ten Electrical Leads for Liquid Hydrostatic Pressures to 60 Kilobars

Abstract: A cylindrical two‐part stainless steel pressure cell with 10 electrical leads that exit directly from a 2.33 cm3 liquid working volume was designed for the generation of hydrostatic pressures to 60 kilobars in a liquid‐solid hybrid system. The structural design, electrical lead system, high pressure liquid seals, and capability of the hydrostatic pressure system are described and discussed. The hydrostatic pressure cell has been used successfully for several years.

The effect of the Coriolis force on the stability of rotating magnetic stars.

Abstract: The effect of the Coriolis force on the stability of rotating magnetic stars in hydrostatic equilibrium is investigated by using the method of the energy principle. It is shown that this effect is to inhibit the onset of instability.

Pressure and Temperature Gradients in Ascending Fluids and Magmas

Abstract: Hydrostatic forces and mechanical strengths limit the flow regimes possible for fluids migrating through channels in the Earth's crust and upper mantle. Temperature changes of fluids probably do not exceed a few tens of degrees during ascent.

An Experimental Study on the Deformation of Materials under High Hydrostatic Pressures : 3rd Report, On Torsional Deformation of Cast Iron

Abstract: It is generally accepted that the flow stress as well as the strain-to-fracture of brittle materials is increased by superposed hydrostatic pressure. However, the fundamentals underlying the effect of hydrostatic pressure on brittle materials are yet to be explained. Torsion tests were carried out on cast iron under hydrostatic pressure up to 4000 kg/cm2 in order to elucidate the effect of hydrostatic pressure on the deformation and fracture of brittle materials. It is shown in this paper that the deformation and fracture properties of cast iron are strongly influenced by the currently acting hydrostatic pressure rather than the strain history of the material. Anisotropy of cast iron usually observed in torsion tests is decreased by hydrostatic pressure.