Twin jets in cross-flow

The multiport diffuser effluent discharge facilities constructed beneath the coastal waters were simplified in the laboratory as twin buoyant jets in a wavy cross-flow environment. The near-field flow structure of twin jets was studied by series of experiments conducted in a physical wave–current flume. The particle image velocimetry (PIV) system was used to measure the velocity field of the jets in various cross-flow-only and wavy cross-flow environments. By means of flow visualization, the distinctive “effluent cloud” (EC) phenomenon was clearly observed and the jet penetration height was found to be notably increased compared with that of cross-flow-only environment at the downstream position. It was found that the wave-to-current velocity ratio Rwc is a very important parameter for effluent discharge. A new characteristic velocity uch and the corresponding characteristic length scale lmb for twin buoyant jets in the wavy cross-flow environment were defined. Using curve-fitting, a new equation to estimate the effects of the jet-to-current velocity ratio (Rjc), wave-to-current velocity ratio (Rwc) and Strouhal number (St) on the jet trajectory were derived to enhance understanding the physical processes underpinning the rise and the dilution of buoyant jets, which is critical to the design of discharge facilities.

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Near-field dynamics of parallel twin jets in cross-flow

Physics of Fluids ◽

10.1063/1.4978856 ◽

2017 ◽

Vol 29 (3) ◽

pp. 035103 ◽

Cited By ~ 5

Author(s):

B. Zang ◽

T. H. New

Keyword(s):

Near Field ◽

Cross Flow ◽

Twin Jets

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DIRECT NUMERICAL SIMULATION OF MULTIPLE JETS IN CROSS-FLOW

Modern Physics Letters B ◽

10.1142/s0217984909018126 ◽

2009 ◽

Vol 23 (03) ◽

pp. 249-252 ◽

Cited By ~ 1

Author(s):

YUFENG YAO

Keyword(s):

Numerical Simulation ◽

Direct Numerical Simulation ◽

Velocity Ratio ◽

Cross Flow ◽

Industrial Applications ◽

Complex Flow ◽

Vortex Pairs ◽

Multiple Jets ◽

Twin Jets ◽

Complex Flow Structure

Direct numerical simulation has been performed to study flow interactions in multiple jets in cross-flow. Configurations considered are twin jets side-by-side and triple jets in tandem. Computations are carried out at the jet to cross-flow velocity ratio of 2.5 and the Reynolds number 225 based on the free-stream quantities and the jet width D . For twin jets, results show that in the vicinity of jet exits, the merging of two counter rotating vortex pairs (CRVP) is strongly dependent on the gap of two jets. Downstream in the far-field, a large single CRVP dominates. The simulation is in qualitatively good agreement with the experimental findings by other researchers. For triple jets, more complicated flow structures are revealed, in which a total of three vortex pairs has been identified, but none of them is dominating. The observations of complex flow structure could assistant relevant industrial applications.

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