Experimental Simulation of a Vertical Round Jet Issuing into an Unsteady Cross-Flow

Lam, K. M.; Xia, Liangyu

doi:10.1061/(asce)0733-9429(2001)127:5(369)

Cited by 16 publications

(5 citation statements)

References 19 publications

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“…Chochua et al (2000) performed computational and experimental investigations on the interaction of a turbulent jet and crossflow. Lam and Xia (2001) experimentally simulated a vertical jet into unsteady crossflow. Wright (1984) investigated the effect of ambient stratification on round, turbulent buoyant jets issuing vertically upwards into uniform crossflow.…”

Section: Modelling Of Turbidity Currents and Jet Injectormentioning

confidence: 99%

Effect of inclined jet screen on turbidity current

Oehy

Cesare

Schleiss

2010

Journal of Hydraulic Research

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The sustainable use of reservoirs for irrigation, flood protection, water supply and hydropower may be endangered due to unavoidable reservoir sedimentation. Turbidity currents are the main process for the transport and deposit of sediments in reservoirs, especially in the deepest part near the dam where vital structures such as power intakes and bottom outlets are located. Besides other measures such as solid or permeable obstacles, turbidity currents can be influenced by means of an inclined water jet screen. Physical experiments of a turbidity current flowing through a water jet screen were carried out. Velocity profiles, front velocities, and deposit evolutions were determined. The results indicate that in certain configurations, turbidity currents can be partially stopped by the jet screen. Furthermore, the deposits downstream of the screen may be reduced up to a factor of two as compared with deposits of a free-flowing turbidity current.

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Section: Modelling Of Turbidity Currents and Jet Injectormentioning

confidence: 99%

Effect of inclined jet screen on turbidity current

Oehy

Cesare

Schleiss

2010

Journal of Hydraulic Research

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“…Traditional wave flumes are not designed for long-term plant exposure experiments, as they do not allow the continuous operation for extended periods necessary for physiological experiments, not to mention their additional requirement of simultaneous replications (La Nafie et al, 2012). To resolve this issue, we adapted a slider-crank mechanism that has been previously used to study the discharge of jets into an oscillatory cross-flow (Lam and Xia, 2001) to create a system by which plants can be exposed under controlled conditions to contrasting wave regimes. In essence, the plants were grown on a swing system that moves the plants continuously back and forth through the water (Fig.…”

Section: Shallow-water Wave Simulatormentioning

confidence: 99%

Physiological and biochemical responses of the salt-marsh plant Spartina alterniflora to long-term wave exposure

et al. 2019

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• Background and Aims Ecosystem-based flood defence including salt-marsh as a key component is increasingly applied worldwide due to its multifunctionality and cost-effectiveness. While numerous experiments have explored the wave-attenuation effects of salt-marsh plants critical to flood protection, little is known about the physiological and biochemical responses of these species to continuous wave exposure. • Methods To address this knowledge gap, we developed a shallow-water wave simulator to expose individual Spartina alterniflora plants to waves in a greenhouse for 8 weeks. S. alterniflora individuals were partially submerged and experienced horizontal sinusoidal motion to mimic plant exposure to shallow water waves. A factorial experiment was used to test the effects of three wave heights (4.1 cm, 5.5 cm and a no-wave control) and two wave periods (2 s and 3 s) on the following key physiological and biochemical plant parameters: plant growth, antioxidant defence and photosynthetic capacity. • Key Results Comparison of wave treatment and control groups supported our hypotheses that wave exposure leads to oxidative stress in plants and suppresses plant photosynthetic capacity and thereby growth. In response, the wave-exposed plants exhibited activated antioxidant enzymes. Comparison between the different wave treatment groups suggested the wave effects to be generally correlated positively with wave height and negatively with wave period, i.e. waves with greater height and frequency imposed more stress on plants. In addition, waveexposed plants tended to allocate more biomass to their roots. Such allocation is favourable because it enhances root anchorage against the wave impact. • Conclusions Simulated wave exposure systems such as the one used here are an effective tool for studying the response of salt-marsh plants to long-term wave exposure, and so help inform ecosystem-based flood defence projects in terms of plant selection, suitable transplantation locations and timing, etc. Given the projected variability of the global wave environment due to climate change, understanding plant response to long-term wave exposure has important implications for salt-marsh conservation and its central role in natural flood defence.

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“…Little has been published, however, in this area. Lam and Xia [11] and Xia and Lam [12] used both laboratory experiments and numerical analyses to investigate the dispersion of a round jet issuing into an unsteady crossflow. They found that the jet effluent was organized into successive large-scale effluent clouds, and the jet width increases at an incremental rate that is strongly affected by the crossflow unsteadiness.…”

Section: Introductionmentioning

confidence: 99%

Flow Dynamics and Mixing of a Transverse Jet in Crossflow—Part II: Oscillating Crossflow

Zhang

Yang

2017

Journal of Engineering for Gas Turbines and Power

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The present work extends Part I of our study to investigate the flow dynamics and scalar mixing of a turbulent gaseous jet in an oscillating crossflow. Attention is first given to intrinsic flow instabilities under a steady condition. Both power spectral density and proper orthogonal decomposition analyses are applied. For the case with a jet-to-crossflow velocity ratio of 4, the two most dynamic modes, corresponding to jet Strouhal numbers of around 0.1 and 0.7, are identified as being closely linked to the shear-layer vortices near the injector orifice and the vertical movement in the jet wake region, respectively. The effect of oscillation imposed externally in the upstream region of the crossflow is also examined systemically at a jet-to-crossflow velocity ratio of 4. A broad range of forcing frequencies and amplitudes are considered. Results reveal that the dominant structures observed in the case with a steady crossflow are suppressed by the harmonic excitations. Flapping–detaching motions, bearing the forcing frequencies and their subharmonics, become dominant as the forcing amplitude increases. The ensuing flow motions lead to the formation of a long, narrow jet plume and a relatively low mixing zone, which substantially alters the mixing efficiencies as compared to the case with a steady crossflow.

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Experimental Simulation of a Vertical Round Jet Issuing into an Unsteady Cross-Flow

Cited by 16 publications

References 19 publications

Effect of inclined jet screen on turbidity current

Effect of inclined jet screen on turbidity current

Physiological and biochemical responses of the salt-marsh plant Spartina alterniflora to long-term wave exposure

Flow Dynamics and Mixing of a Transverse Jet in Crossflow—Part II: Oscillating Crossflow

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