Hydrostatic equilibrium

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

Numerical model of viscous debris flows with depth-dependent yield strength

Abstract: Non-Newtonian fluids such as Bingham model have been widely used to simulate the motion of viscous debris flow. The materials will flow only if shear stresses exceed its yield strength, and the integrals along the depth can be performed in the shear layer and plug layer, respectively. The pore-water pressure is considered in the rheological model according to the physical properties of viscous debris flow. In addition, the lateral pressure in horizontal direction inner debris flow is different from hydrostatic assumptions due to the presence of particles, the earth pressure coefficient with Savage-Hutter assumption is added into the governing equations. The governing equations of debris flow are solved by using Lagrange difference method, and the effects of material parameters, earth pressure coefficient and inclination angle on the runout characteristics such as velocity distribution, runout distance and deposit shape are analyzed. Numerical results show that the debris flow starts to move due to the gravity, the velocities vary almost linearly, and the rear end of debris flow moves backward because the inclination angle of plane is very small. Finally, it stops due to the basal friction force and the maximum final height locates the start position of horizontal section. Recent studies have suggested that the earth pressure coefficient mainly influences on the depth profile of granular flow, however, these phenomena have not been captured in the numerical results for debris flow perhaps due to the small inclination angle. Further studies are needed to determine the effects of earth pressure coefficient on the natural debris flow with more complex topography.

Hydrodynamic “memory” of binary fluid mixtures

Abstract: A theoretical analysis is presented of hydrostatic adjustment in a two-component fluid system, such as seawater stratified with respect to temperature and salinity. Both linear approximation and nonlinear problem are investigated. It is shown that scenarios of relaxation to a hydrostatically balanced state in binary fluid mixtures may substantially differ from hydrostatic adjustment in fluids that can be stratified only with respect to temperature. In particular, inviscid two-component fluids have “memory”: a horizontally nonuniform disturbance in the initial temperature or salinity distribution does not vanish even at the final stage, transforming into a persistent thermohaline “trace.” Despite stability of density stratification and convective stability of the fluid system by all known criteria, an initial temperature disturbance may not decay and may even increase in amplitude. Moreover, its sign may change (depending on the relative contributions of temperature and salinity to stable background density stratification). Hydrostatic adjustment may involve development of discontinuous distributions from smooth initial temperature or concentration distributions. These properties of two-component fluids explain, in particular, the occurrence of persistent horizontally or vertically nonuniform temperature and salinity distributions in the ocean, including discontinuous ones.

Porous hydrostatic pressure bearing structure based on hydrophobic interfaces

Abstract: The invention discloses a porous hydrostatic pressure bearing structure based on hydrophobic interfaces. The porous hydrostatic pressure bearing structure comprises a hydrostatic pressure bearing pad and a rotating shaft, wherein the hydrostatic pressure bearing pad sleeves the rotating shaft, and an annular hydrostatic pressure water trough is formed in an outer cylindrical surface of the hydrostatic pressure bearing pad. The porous hydrostatic bearing has the sliding surface of the hydrostatic pressure bearing pad made from a porous ceramic material and the sliding surface of the rotating shaft made from an alloy material, and hydrophobic or super-hydrophobic material interfaces are formed in the sliding surfaces of the hydrostatic pressure bearing pad and the rotating shaft by means of forming fine coarse structure interfaces or modifying low surface energy material interfaces, so that the friction resistance of the bearing under the condition of high speed is reduced, and the friction power consumption and temperature rise of the bearing are reduced.

Theoretical Research on the Design of Hydrostatic Bearingin Water Hydraulic Piston Pump

Abstract: Hydrostatic bearing acts an important role in water hydraulic piston pump,such as the pair of slipper pad and the pair of valve plate.Presently there are two methods for designing hydrostatic bearing.Which one should be chosen in water hydraulic area depends on the accuracy of the methods.Naver-Stokes equation of uncompressible viscous fluid is the foundation of hydrostatic bearing design,based on which a new formulation could be mathematically deduced.The form of this new formulation tallies with physical model very well.

Effect of Moisture on the Hydrostatic Pressure

Abstract: This Note describes a method of deriving a modified form of the hydrostatic equation by making allowance for the presence of moisture in an atmospheric column.