Hydrostatic equilibrium

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

Bifurcations of the modal structure of internal waves in a fluid induced by a spatially periodical variation of the hydrostatic stability parameter

Abstract: The dispersion law of internal gravity waves in a stratified fluid at rest is investigated: it is shown that the introduction of an oscillating component of the stratification parameter along the vertical direction introduces an infinite number of branches of the dispersion relation. The importance of this effect for the estimate of the triadic nonlinear interaction between internal waves is suggested as one of the most relevant consequences of the results reported.

Experimental Investigation on the Impact of Dam-Break Induced Surges on a Vertical Wall

Abstract: This paper presents the results of an experimental investigation on the impact of dam-break-induced surges on a vertical wall. The instantaneous surge height and dynamic pressure on a vertical wall were measured for surges with different reservoir depths of H = 200 mm, 250 mm, and 300 mm. The time-histories of horizontal pressure on the wall were measured using the miniaturized pressure transducers, and the surge heights were recorded with an ultrasonic sensor. The relationships between dynamic pressure and surge height on the vertical wall and during the impact were obtained from recorded raw data. The experimental results highlighted detailed processes on the variation of impact pressure during the surge propagation, impact on the wall, runup, falling, and breakup of the turbulent flow. The time-histories of surge height and dynamic pressure were analyzed, and the results were compared with the hydrostatic pressure on the wall to study wave breaking mechanism of tsunami waves on the wall. Dynamic pressures at the impact instant were found to be approximately three times the corresponding static pressure in the bed, in good agreement with previous research Moreover, the maximum surge runup heights on the wall were between 2.1 and 2.3 times the corresponding initial reservoir depths. The vertical distributions of impact pressure were divided into two hydrodynamic regimes. Based on the impact duration, the first regime occurred less than 0.1 s after the impact with highly non-linear pressure distributions, and the second regime showed a semi-hydrostatic pressure distribution from 0.5 s to 0.7 s. The results presented in this study are suitable for the design of coastal infrastructures and can be used to validate numerical models.

Investigation of the Mechanical Behaviour of Lingulid Sandstone Emphasising the Influence from Pre-Existing Structural Defects, Part 1: Model Identification Based on Static Experiments

Abstract: A constitutive model able to describe both tensile damage and plastic deformation under confinement is a prerequisite to numerically simulate the behaviour of sandstone rock under an impact loading induced in a percussive drilling process. Therefore, model identification under both tensile and high confinement states is needed. In the present work, an experimental investigation was carried out in order to determine the mechanical properties of a sandstone rock for the purpose of advanced constitutive model identification. Different testing methods were used in quasistatic and dynamic loading regimes. This first part of the study is dedicated to static experiments, whereby three-point bend tests were first performed to evaluate the quasistatic tensile strength of the rock and its distribution by employing the Weibull statistics. Secondly, direct compression tests were conducted to evaluate the stiffness and strength in an unconfined condition. Afterwards, quasioedometric compression (QOC) tests were carried out in order to obtain the deviatoric and volumetric behaviours of the material as a function of the hydrostatic pressure (up to 375 MPa). In these QOC tests, the metallic confinement cell was instrumented with strain gauges to deduce the state of the stress and strain within the sample. A linear volumetric response along with a continuous increase of strength with the level of hydrostatic pressure was observed. This experimental work points out that, under unconfined loading (three-point bending and uniaxial compression), pre-existing structural defects play a major role leading to a highly scattered behaviour in terms of sample stiffness and ultimate applied load. On the other hand, under high confinement levels (QOC tests), beyond the nonlinear response of the curve foot, the influence from structural defects was observed to be small.

Investigation of sloshing in the prismatic tank with vertical and t-shape baffles

Abstract: The demand for liquid carriers, such as liquefied natural gas (LNG), has increased in recent years. One of the most common types of LNG carriers is the membrane type, which is often built by a shipyard with a prismatic tank shape. This carrier is commonly known for its effective ways to mitigate sloshing using a baffle. Therefore, this study was performed to evaluate sloshing in a prismatic tank using vertical and T-shape baffles. The sloshing was conducted with 25% and 50% filling ratios because it deals with the nonlinear free-surface flow. Furthermore, the smoothed particle hydrodynamics (SPH) was used to overcome sloshing with ratio of a baffle and water depth is 0.9. A comparison was made for the dynamic pressure with the experiment. The results show that SPH has an acceptable accuracy for dynamic and hydrostatic pressures. Baffle installation significantly decreases the wave height, dynamic pressure and hydrodynamic force.