Closure to "Air-Water Flows and Head Losses on Stepped Spillways with Inclined Steps"

Air–water properties of unsteady breaking bores part 1: Novel Eulerian and Lagrangian velocity measurements using intrusive and non-intrusive techniques

Transient motion, turbulence and bubble dynamics make any velocity quantification extremely difficult in unsteady gas–liquid flows. In the present study, novel Eulerian and Lagrangian techniques of velocimetry were developed, using both intrusive and non-intrusive measurements. The selected unsteady gas–liquid flow was a breaking bore,...

Air–water properties of unsteady breaking bore part 2: Void fraction and bubble statistics

Continuing from the part 1 (Shi et al., 2022) this paper presents an experimental investigation of transient void fraction and bubble statistics in a highly turbulent breaking bore with Fr₁=2.4. The measurements were conducted using a combination of dual-tip phase-detection probes and an ultra-high-speed video camera. The enclosed...

Effect of probe size on phase-detection probe measurements of air-water flow properties in hydraulic jumps

This experimental study investigated the air-water flow properties and bubble characteristics in hydraulic jumps with Froude numbers Fr₁ = 2.4 and 6.3, using four dual-tip phase detection probes with sensor sizes from 0.25 mm to 0.64 mm. The hydraulic jumps were characterized by a fully breaking roller with substantial air...

Discussion of "Performance of Intrusive Phase-Detection Probe with Large Sensor Size in Air-Water Flow Measurement and Application to Prototype Hydraulic Jump Study"

Discussion of "transverse Nonuniformity of Air-Water Flow and Lateral Wall Effects in Quasi-Two-Dimensional Hydraulic Jump"

Hydraulic jumps with low inflow Froude numbers: air–water surface patterns and transverse distributions of two-phase flow properties

Abstract: Hydraulic jumps are commonly employed as energy dissipators to guarantee long-term operation of hydraulic structures. A comprehensive and in-depth understanding of their main features is therefore fundamental. In this context, the current study focused on hydraulic jumps with low Froude numbers, i.e. Fr₁ = 2.1 and 2.4, at...

Aeration performances and air—Water mass transfer on steep stepped weirs with horizontal and inclined steps

At hydraulic structures, some strong interactions may develop between fast flowing waters and the air adjacent to the water in motion that enhance the air-water transfer of atmospheric and volatile gases in the flow. In turn, in-stream structures may contribute to the aeration and re-oxygenation during overflow. The present study aims to...

Ensemble-statistical approach in the measurement of air-water flow properties in highly unsteady breaking bores

Breaking bores are commonly observed in a number of natural processes, often associated with the presence of a transient mixture of air and water, with intense recirculation, air bubble entrainment, and splashing. Two-phase flow measurements in such highly unsteady flows cannot be based on long-duration measurements and require novel ensemble...

Air-Water Flows and Head Losses on Stepped Spillways with Inclined Steps

On a stepped spillway, the staircase invert profile generates some intense turbulent dissipation during the spill, associated with a significant reduction of kinetic energy, as well as strong self-aeration. The present study focused on the effects of inclined downward steps on the air-water flow properties, flow resistance, and head losses...

Intrusive and non-intrusive two-phase air-water measurements on stepped spillways: A physical study

Self-aerated free-surface flow studies have a more recent history compared to classical fluid dynamics. Traditional velocimetry techniques are adversely affected by the presence of gas–liquid interfaces. In the present study, detailed air-water flow measurements were performed in a highly turbulent free-surface flow, and three velocimetry...

Strong free-surface turbulence in breaking bores: A physical study on the free-surface dynamics and air-water interfacial features

Highly turbulent free-surface flows are characterised by complex and rapidly varying air-water surface features, leading to enhanced surface roughness, breakup and disintegration processes. Such a strong free-surface turbulence has an impact on a number of environmental flows, and a deeper understanding of its physical nature is fundamental....