Hydrostatic equilibrium

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

The hydraulics problem in slope stability analysis

Abstract: Hydraulic pressures and forces are obtained on a typical slice, as used in current methods of slope stability analysis, under hydrostatic and flowing groundwater conditions It is shown that current methods do not satisfy some basic hydraulics and soil mechanics principles The effective normal stress on the lower boundary of a slice is shown to be underestimated, and the resultant hydraulic force is not accounted for adequately Key words: effective stress, hydraulic pressure, hydraulic gradient, hydraulic force, slope stability

Computation of Ellipsoidal Mass Distributions

Abstract: : The present report studies the computation of density distributions for the reference ellipsoid using a spherical-harmonic expansion to the second order in the flattening. The computational formulas are given and, as an example, a polynomial model is calculated. It is found that, for each density distribution in hydrostatic equilibrium, there exists a corresponding ellipsoidal configuration such that corresponding internal level surfaces have very nearly the same flattening. The deviations of ellipsoidal mass distributions from hydrostatic equilibrium figures are investigated, and formulas and numerical estimates are given for the separation between surfaces of constant density and surfaces of constant potential, and for nonhydrostatic stress differences. (Author)

Three-dimensional hydrostatic modeling of a bay coastal area

Abstract: This article describes the development of a three-dimensional (3D) multilayer hydrostatic model of tidal motions in the Ariake Sea and its application. The governing equations were derived from 3D Navier-Stokes equations and were solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. This study introduced a 3D, time-dependent, hydrostatic, tidal current model that can compute wetting and drying in tidal flats due to tidal motion. The 3D model was first tested against analytical solutions for three standard cases in a rectangular basin in order to investigate the performance of the model. Then, the model was applied to Saigo fishery port and the Ariake Sea. For standard cases, the numerical solutions were almost identical to the analytical solutions. Finally, the model results for Saigo port and the Ariake Sea show good agreement with the field observations.

Analysis of a mogi-type model describing surface deformations induced by a magma chamber embedded in an elastic half-space

Abstract: Motivated by a vulcanological problem, we establish a sound mathematical approach for surface deformation effects generated by a magma chamber embedded into Earth's interior and exerting on it a uniform hydrostatic pressure. Modeling assumptions translate the problem into classical elasto-static system (homogeneous and isotropic) in an half-space with an embedded cavity. The boundary conditions are traction-free for the air/crust boundary and uniformly hydrostatic for the crust/chamber boundary. These are complemented with zero-displacement condition at infinity (with decay rate). After a short presentation of the model and of its geophysical interest, we establish the well-posedness of the problem and provide an appropriate integral formulation for its solution for cavity with general shape. Based on that, assuming that the chamber is centred at some fixed point $\bm{z}$ and has diameter $\varepsilon>0$, small with respect to the depth $d$, we derive rigorously the principal term in the asymptotic expansion for the surface deformation as $\varepsilon=r/d\to 0^+$. Such formula provides a rigorous proof of the Mogi point source model in the case of spherical cavities generalizing it to the case of cavities of arbitrary shape.

ASUCA: The JMA Operational Non-hydrostatic Model

Abstract: The non-hydrostatic numerical weather prediction (NWP) model ASUCA developed by the Japan Meteorological Agency (JMA) was launched into operation as 2 and 5 km-resolution regional models in 2015 and 2017, respectively. This paper outlines specifications of ASUCA with focus on the dynamical core and its configuration/accuracy as an operational model. ASUCA is designed for high computational stability and efficiency, mass conservation and forecast accuracy. High computational stability is achieved via a time-split integration scheme to compute acoustic terms and an advection scheme with a flux-limiter function to avoid numerical oscillation. In addition, vertical advection and sedimentation are calculated together with another exclusive time-splitting technique. ASUCA adopts hybrid parallelization using Message Passing Interface (MPI) and Open Multi Processing (OpenMP) for high computational efficiency on massive parallel scalar computers. The three-dimensional arrays are allocated such that the vertical direction is the stride-one innermost dimension to make effective use of cache and multi-thread parallelization. This is particularly advantageous for physical processes evaluated in a vertical column. To ensure mass conservation, density rather than pressure is integrated as a prognostic variable in flux-form fully compressible governing equations. ASUCA exhibited better performance than the previous operational model in idealized and NWP tests.