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Better understanding of the hydraulic performance of stormwater inlets which serve as the linkage between the surface drainage system and the underground sewer system is important to avoid ...

This paper presents a retrofit for vortex settling basins (VSBs) by perforating the deflector to reduce sediment deposition and thereby lowering VSB failure risks. Experiments were conducte...

This paper presents an analytical study of mass transfer from a single bubble rising in stagnant water and its size variation. A model for bubble–water mass transfer was established and val...

This study experimentally investigated the axis switching of free-falling water jets issued from an elliptical nozzle with an aspect ratio of 1.6. High-speed photography was used to capture...

Theoretical and laboratory studies were presented for the water column oscillation in a vertical tube partially immersed in a reservoir. Three types of oscillations were studied, with the t...

Plunging-flow dropshafts can entrain a large amount of air into sewer systems, pressurize downstream airspace, and cause potential sewer odor issues. In this study, a new design for a plung...

Energy dissipation is one of the main considerations in the design of drop manholes and is closely related to the flow regimes observed. Four flow regimes in a drop manhole are classified a...

A physical model study was conducted to investigate the mechanisms of air entrainment in a tall plunging dropshaft of 7.7 m in height. The water flow in the dropshaft was observed to break up into small drops of approximately a few millimeters diameter at a drop height of 5 m. The dominant water drops were found to be approximately 2 mm and they fell at an average speed of approximately 6 m/s. An analytical model was developed to predict the amount of air drag and air flow needed on the basis of the momentum transfer from the water drops. The drag force induced a vertical air pressure gradient, and the model prediction compared well with the measurements. The entrained air flow rate increased with the water flow rate, but the ratio of the air to water flow rate decreased from approximately 20 to 5 times when the water flow rate increased from 3.9 to 47.7 L/s. The air pressure was negative at the top of the dropshaft to allow the ambient air to be entrained, and it increased to the atmospheric pr...

An experimental study on the breakup of a turbulent round-water jet in still air with a nozzle Reynolds number of 145,600 and Weber number of 10,400 is reported. The visual structure of the falling water jet was recorded by a high-speed camera, and the characteristics of the falling jet were investigated. As the jet travelled from the nozzle, initial surface disturbances grew, and the lateral oscillation of the jet surface was amplified. The jet thickness initially increased and then decreased because of the combined effects of lateral turbulence fluctuation and gravitational acceleration. The amplitude of the surface disturbance grew in an exponential form. Based on the averaged transverse-water distribution, the water jet spreading rate was found to vary between 0.5 and 1.8%, and the decay of the jet water core had an average value of 0.7%. The onset of jet breakup was found at a distance of approximately 100 times of the nozzle diameter. A theoretical model was developed for predicting the onse...