Showing papers on "Hydrostatic equilibrium published in 1980"

Is the sun constant

Abstract: Small fluctuations in the solar constant can occur on time scales much shorter than the Kelvin time. Changes in the ability of convection to transmit energy through the superadiabatic and transition regions of the convection zone cause structure adjustments which can occur on a time scale of days. The bulk of the convection zone reacts to maintain hydrostatic equilibrium (though not thermal equilibrium) and causes a luminosity change. While small radius variations will occur, most of the change will be seen in temperature.

Instrumental measuring method for determining the size-distribution of grained material

Abstract: An instrumental measuring method for determining the size-distribution of grained material is described in which the material is evenly distributed in a fluid then the fluid is let in rest state when the materials gets sedimenting, and during sedimentation the hydrostatic pressure is continuously measured in at least two height regions of the fluid preferably by appropriate pressure sensitive transistors and the difference of the measured hydrostatic pressures is characteristic of the size-distribution of the grained material on the basis of the well-known Stokes' relation.

Solving for Temperature Using Unnaturally Latticed Hydrostatic Equations

Abstract: Analyzing and balancing wind and mass fields on constant pressure surfaces and then interpolating the results to model coordinates cause significant errors, which lower verification scores and create inertial gravity noise. Although interpolation of geopotential to model coordinates produces less error, the computation of temperature with the model finite difference equations may lead to very large errors, as demonstrated by computation with standard atmosphere profiles. The solution for temperature using a variational formalism together with the model hydrostatic equation provides a method that greatly decreases the error in computation of pressure height by the model. The procedure is derived and results given for two different forms of Arakawa's hydrostatic equation. One of these forms an ill-conditioned equation set when geopotential is used to compute temperature. The results show that a significant decrease in the errors of geopotential produced by the model occurs when the variational proc...

Asymptotic derivation of the ageostrophic model for atmospheric hydrostatic flows

Abstract: Starting from hydrostatic non-adiabatic equations for atmospheric flows, we use a matched asymptotic expansion technique, with the Kibel, Ekman and Mach numbers as small parameters, the last two of them being related in a definite way to the first one. We derive, as a first approximation, the quasi-geostrophic equation and in a second approximation the ageostrophic equation which is consistent with the scheme of expansion. A brief account is given of the various initial and boundary layers.

The heating of a thermally conducting stratified medium. II - A simple plane model of an atmosphere

Abstract: Exact solutions of the following theoretical problem are presented: A plane atmosphere is in hydrostatic equilibrium with a uniform gravity The ideal gas law is assumed Heat is generated everywhere at a rate proportional to the local density The atmosphere is maintained in a steady state through cooling by thermal conduction and radiation This problem is reducible to quadratures for a thermal conductivity which is an arbitrary, but prescribed, function of the temperature, and for a radiative loss which is expressible as the product of the density and an arbitrary, but prescribed, function of the pressure The analysis is carried out for the case of power law thermal conductivity, and a radiative loss proportional to the square of the density and to the first power of the temperature The radiative cooling function adopted here has the basic mathematical form for an optically thin medium The solutions reproduce the macroscopic ordering of a hot 'corona' separated from a 'photosphere' by a layer of temperature minimum The analytic solutions allow direct illustration of the interplay between steady energy transport and the requirements of hydrostatic equilibrium

Prediction of Annulus Pressure Gradients in Pumping Wells

Abstract: Experimental data on pressure gradients were obtained for gas bubbling through static liquids in various concentric annulus configurations with eight different liquids. Although a definite liquid physical property effect exists, the Gilbert S curve gave an adequate representation of the data. A more accurate correlation was developed, together with a physical model that separates hydrostatic and friction components of the pressure gradient.

A review of the different liquid core models used for the computation of the dynamical effects on nutations and earth tides

Abstract: The first approximation of the figure of a fluid planet is obtained by assuming hydrostatic equilibrium with respect to its gravitational self-attraction and the centrifugal force. When the speed of rotation is not too fast, the equipotential surfaces may be considered to an excellent approximation as ellipsoids of revolution. It is easy to show that these hydrostatic equipotential surfaces are surfaces of equal density (ρ).

A Review of the Different Liquid Core Models Used for the Computation of the Dynamical Effects on Nutations and Earth Tides

Abstract: The first approximation of the figure of a fluid planet is obtained by assuming hydrostatic equilibrium with respect to its gravitational self-attraction and the centrifugal force. When the speed of rotation is not too fast, the equipotential surfaces may be considered to an excellent approximation as ellipsoids of revolution. It is easy to show that these hydrostatic equipotential surfaces are surfaces of equal density (ρ).

Radial motion of a solid spherical body in a magnetic field

Abstract: The object of the present paper is to investigate the radial motion of a solid spherical body, assumed to be homogeneous, isotropic and elastic, in presence of a magnetic field in the azimuthal direction. The body is assumed to be in a state of initial stress which is hydrostatic in nature. This theory of radial motion of a solid spherical body in a magnetic field has been utilised to find the small radial motion of a solid Earth assumed to be homogeneous isotropic elastic sphere in presence of a magnetic field in the azimuthal direction. Considering the effect of gravity and the initial stress produced by slow process of creep due to extra masses over the surface of the Earth, the fundamental equations of motion are derived which are non-linear in character and are solved. The times of a desired radial displacement are calculated in presence of a magnetic field only and in presence of the same magnetic field, initial stress and gravitational field, which are compared and exhibited numerically.

The Hydrodynamic Force Acting on the Ship in a Following Sea (1 st Report)

Abstract: Broaching phenomena are most likely to occur in a following sea to relative small and fast craft under the condition that the wavelength/the ship length ratio is about 1. 5 to 2. 0. There are many studies and explanations about it, and it is thought that the forces acting on the ship are almost consist of the hydrostatic force and steady state lift.Towing flat plate model in following waves without attack angle it become obvious that side force and heading moment are of such magnitude as to a marked extend. These changed or additional disturbing forces depend upon the wave height and upon the relative position of the ship to waves.In this paper two attempt are made in order to investigate the hydrodynamic force. Firstly, transforming vortex core model is used under the assumption of the free surface is flat. Slender-rectangular thin wing in the constant stream, 3-dimensional separation occurs at the end of the side edges, which form a symmetrical spiral vortex sheet.In a following sea, these spiral vortex sheet may be affected by the wave orbital velocity. A simple flow model, consists of core vortices and feed vortex sheets which emerge from side edges to the core vortices, is used.And core vortices are transformed by the wave orbital velocity and the induced velocities of vortices. By the method, reasonable results are obtained for normal force coefficient, centre of pressure and location of the core vortex in the constant flow. But in a following sea, calculated normal force coefficient is not so good.Secondly, high speed slender body theory is used introducing the data of incident wave as free surface.These method, calculated normal force and heading moment coefficients show quite good agreement to the data obtained from towing flat plate model test.

Hydrostatic tidal model for lunar asymmetry

Abstract: A hydrostatic tidal model is presented which can successfully account for the two major features of lunar asymmetry. These are the observed offset between the centre of figure and the centre of mas...