abstract bottom rack intake is one of the most appropriate structures for diverting water in steep rivers. the problems of corrosion, deformity and clogging of the bottom racks in long term, inspires a new system of bottom intake in which a filled trench of porous media is replaced by the bottom racks. diversion of a specified amount of discharge through the porous media when void space in the ...

In this study, gas evolution in a vertical electrochemical cell is investigated numerically with a modified two-fluid model. The mathematical model involves solution of separate transport equation for the gas and liquid phases with an allowance to inter-phase transfer of mass and momentum. The governing equations are discreted via the finite volume technique and then are solved by ...

A procedure is described for limiting the void fraction in fluid particle systems, computed by means of numerical multiphase flow simulation codes, to values which do not fall below those realisable in practice. It is based on a computation of the particle /particle contact forces which come into play only when computed void fractions fall to values below those corresponding to random packing o...

When a refrigeration plant operates with a large difference between condensing and evaporating pressures, multistage operation is required to obtain an acceptable performance. In two-stage systems, vessels that combine flash-gas removal and intercooling are commonly used. The disadvantage of these vessels is the large amount of refrigerant required for proper operation. An alternative for these...

The impedance measurement between a pair of flush-mounted electrodes was used to measure the characteristics of a stratified near-wall bubbly flow. The variation in cross electrode impedance with liquid layer thickness and mixture void fraction was examined using numerical simulations and static experiments. The experimental realization of the measurement system was used to measure the solid fr...

Abstract Recently, one of the authors suggested calculating void fraction, an essential element in thermalhydraulics, working with the ‘thermodynamic’ quality instead of the usual ‘flow’ quality. However, the standard heat balance is currently stated as a function of the ‘flow’ quality. Therefore, we should search a new energy balance between the mixture enthalpy, based on ‘thermodynamic’ quali...

Flood waves resulting from dam breaks and flash floods have been responsible for numerous losses. In the present study, sudden flood releases were investigated down a large stepped waterway initially dry. A new experimental technique was developed to obtain instantaneous void fractions, bubble count rates and velocities. Unsteady air-water flow properties were recorded with arrays of conductivi...

PURPOSE To evaluate magnetic resonance (MR) imaging-based quantitative phase-contrast cerebrospinal fluid (CSF) velocity imaging for prediction of successful shunting in patients with normal-pressure hydrocephalus (NPH). MATERIALS AND METHODS Eighteen patients (mean age, 73 years) with NPH underwent routine MR imaging and CSF velocity MR imaging before ventriculoperitoneal (VP) shunting. The ...

Gas-liquid flow is extensively used in industrial systems such as power generation units, cooling and heating systems (i.e. condensers, evaporators and manifolds), safety valves, etc. These systems generally have complex geometries composed by singularities like expansion, contraction, bends and orifices. Thus two-phase flow characteristics through these singularities should be identified in or...