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Hydrostatic equilibrium

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


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Hongbo Du1, Feng Dai1, Mingdong Wei1, Ang Li1, Zelin Yan1 
TL;DR: In this article, a combined dynamic compression-shear test was performed on inclined cylindrical sandstone specimens with hydrostatic confining pressures and showed that the shear component in the dynamic load limits the dynamic peak stress of rocks.
Abstract: Rocks in the deep underground are likely subjected to both hydrostatic confining pressure and dynamic compression–shear load. Thus, accurately characterizing the dynamic properties and failure mechanism of hydrostatically confined rocks under combined compression–shear impacting is crucial for the stability assessment of deep underground rock structures. In this study, on the basis of an improved split Hopkinson pressure bar (SHPB) apparatus, the combined dynamic compression–shear tests are performed on inclined cylindrical sandstone specimens with hydrostatic confining pressures. During the test, the dynamic force balance of rock specimens can be well satisfied using the pulse shaping technique. Our results show that the hydrostatic confining pressure and dynamic loading rate help strengthen the load-carrying capacity of rocks. In contrast, the shear component in the dynamic load limits the dynamic peak stress of rocks. As hydrostatic confining pressure increases, the failure surface based on the Drucker–Prager criterion gradually expands outward. Under dynamic loading, the compressive deformation modulus of rocks decreases with increasing shear component in the dynamic load, contrary to its response to hydrostatic confining pressure. Fragmentation analysis indicates that the hydrostatic confining pressure and the shear component of dynamic loading restrict the fracture behavior of rocks. Besides, as the specimen inclination angle and the hydrostatic confining pressure increase, the failure pattern of rock specimens changes from the tensile-dominated failure with a truncated conical surface to the shear-dominated failure with a single shear plane along its short diagonal.

23 citations

Journal ArticleDOI
TL;DR: In this article, the effects of K-mouflage on the dynamics of clusters of galaxies were investigated at both background cosmology and cosmological perturbations levels, focusing on cases where the pressure emanates from small-scale nonlinear physics.
Abstract: We investigate the effects of a K-mouflage modification of gravity on the dynamics of clusters of galaxies. We extend the description of K-mouflage to situations where the scalar field responsible for the modification of gravity is coupled to a perfect fluid with pressure. We describe the coupled system at both the background cosmology and cosmological perturbations levels, focusing on cases where the pressure emanates from small-scale nonlinear physics. We derive these properties in both the Einstein and Jordan frames, as these two frames already differ by a few percents at the background level for K-mouflage scenarios, and next compute cluster properties in the Jordan frame that is better suited to these observations. Galaxy clusters are not screened by the K-mouflage mechanism and therefore feel the modification of gravity in a maximal way. This implies that the halo mass function deviates from $\Lambda$-CDM by a factor of order one for masses $M\gtrsim 10^{14} \ h^{-1} M_\odot$. We then consider the hydrostatic equilibrium of gases embedded in galaxy clusters and the consequences of K-mouflage on the X-ray cluster luminosity, the gas temperature, and the Sunyaev-Zel'dovich effect. We find that the cluster temperature function, and more generally number counts, are largely affected by K-mouflage, mainly due to the increased cluster abundance in these models. Other scaling relations such as the mass-temperature and the temperature-luminosity relations are only modified at the percent level due to the constraints on K-mouflage from local Solar System tests.

23 citations

Journal ArticleDOI
TL;DR: In this article, the adjustment of a compressible, stably stratified atmosphere to sources of hydrostatic and geostrophic imbalance using a linear model is investigated using a time-dependent injections of mass, heat, or momentum that model those processes considered "external" to the scales of motion on which the linearization and other model assumptions are justifiable.
Abstract: The adjustment of a compressible, stably stratified atmosphere to sources of hydrostatic and geostrophic imbalance is investigated using a linear model. Imbalance is produced by prescribed, time-dependent injections of mass, heat, or momentum that model those processes considered “external” to the scales of motion on which the linearization and other model assumptions are justifiable. Solutions are demonstrated in response to a localized warming characteristic of small isolated clouds, larger thunderstorms, and convective systems. For a semi-infinite atmosphere, solutions consist of a set of vertical modes of continuously varying wavenumber, each of which contains time dependencies classified as steady, acoustic wave, and buoyancy wave contributions. Additionally, a rigid lower-boundary condition implies the existence of a discrete mode—the Lamb mode— containing only a steady and acoustic wave contribution. The forced solutions are generalized in terms of a temporal Green's function, which repres...

23 citations

Journal ArticleDOI
TL;DR: In this paper, the interior of Rhea is modeled based on observational constraints and the results from geodynamical models available in the literature, and the degree-two gravity coefficients are computed for each of these models in order to assess which properties of the interior are likely to be inferred from Cassini radio science measurements scheduled on 26 November 2005.
Abstract: We model the interior of Rhea on the basis of observational constraints and the results from geodynamical models available in the literature. Ten main types of models are defined, depending on the presence or absence of a high-pressure ice layer (ice II), and the extent of separation of the rock component from the volatiles. The degree-two gravity coefficients are computed for each of these models in order to assess which properties of the interior are likely to be inferred from Cassini radio science measurements scheduled on 26 November 2005. C22 greater than 2.5 x 10(exp -4) indicates that the satellite is undifferentiated, except for a slight increase in density with depth resulting from material self-compression. C22 between 1.67 x 10(exp -4)(lower bound) and 1.90 x 10(exp -4) indicates the presence of a rocky core, whose radius can be determined from the satellite's mass and ices densities, for a given temperature profile. For other values, most of the ten models cannot be distinguished from each other. However, assumptions on the density of the rock phase, presence or absence of ice II, and the degree of differentiation could allow a unique model to be determined in many cases. While the calculation presented in this work assumes that Rhea is in hydrostatic equilibrium, it is likely that Rhea' gravity field is partly affected by nonhydrostatic anomalies.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of the Delft3D-Flow hydrodynamic modeling of a tortuously meandering river is studied. And the results of the nonhydrostatic version of Delft-3D are discussed.
Abstract: Given the importance of pressure gradients in driving secondary flow, it is worth studying how the modelled flow structures in a natural river bend can be impacted by the assumption of hydrodynamic pressure. In this paper, the performance of hydrostatic versus nonhydrostatic pressure assumption in the three-dimensional (3D) hydrodynamic modelling of a tortuously meandering river is studied. Both hydrostatic and nonhydrostatic numerical models were developed using Delft3D-Flow to predict the 3D flow field in a reach of Stillwater Creek in Ottawa, Canada. An acoustic Doppler velocimeter was employed to measure the 3D flow field at a section in a sharp bend of the simulated river at two flow stages. The results of the Delft3D hydrostatic model agreed well with the acoustic Doppler velocimeter measurements: The hydrostatic model predicted reasonably accurately both the streamwise velocity distribution across the section and the magnitude and location of the primary secondary flow cell. The results of the Delft3D nonhydrostatic approximation showed that the model was not conservative and could not accurately generate either the secondary flow or the streamwise velocity distribution. This study illustrated the superior performance of the hydrostatic over nonhydrostatic 3D modelling of the secondary flow using Delft3D. Several possible reasons for unfavourable performance of the nonhydrostatic version of Delft3D are discussed, including the pressure correction technique employed in Delft3D. Considering the uncertainties that may arise in both modelling and field measurements, the 3D hydrostatic Delft3D model was capable of reasonably predicting the river bend flow structures in the studied meandering creek.

23 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023282
2022708
202167
202089
201998
201893