Triple decomposition technique in air-water flows: application to instationary flows on a stepped spillway

Felder, Stefan and Chanson, Hubert (2014) Triple decomposition technique in air-water flows: application to instationary flows on a stepped spillway. International Journal of Multiphase Flow, 58 139-153. doi:10.1016/j.ijmultiphaseflow.2013.09.006

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Author Felder, Stefan
Chanson, Hubert
Title Triple decomposition technique in air-water flows: application to instationary flows on a stepped spillway
Journal name International Journal of Multiphase Flow   Check publisher's open access policy
ISSN 0301-9322
Publication date 2014-01
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.ijmultiphaseflow.2013.09.006
Open Access Status File (Author Post-print)
Volume 58
Start page 139
End page 153
Total pages 15
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon
Collection year 2014
Language eng
Formatted abstract
• Instabilities in air–water flows yielding very large turbulence levels.
• New triple decomposition approach for highly aerated instationary flows.
• Air–water flow experiments were conducted on stepped spillways with slope of θ = 8.9°.
• Slow fluctuating components contained main turbulent kinetic energy.
• Fast fluctuating component has similar turbulence levels to flat stepped chute.

Self-sustained instabilities and pseudo-periodic motion may be observed in hydraulic structures and industrial flows. Documented examples include the hydraulic jump, sloshing motion in a reservoir and surging waves in pooled stepped spillways. The instabilities may generate some very large turbulence levels and integral turbulent scales, combining the contributions of both slow fluctuations and fast turbulent fluctuations. Herein a triple decomposition of phase-detection probe signals was developed to identify the turbulent contributions of the slow and fast velocity components in highly aerated free-surface flows. The raw probe signals were split into slow and fast signal components and the air–water flow properties of each component were calculated. The method was applied to a new data set collected down a stepped spillway channel with two stepped configurations (flat and pooled). The latter configuration experienced some self-sustained pseudo-periodic instabilities. The data analysis results showed that the fast turbulent velocity fluctuations of the decomposed signal were close to the turbulence levels on the flat stepped spillway (i.e. in absence of instability). And the largest turbulent energy was contained in the slow fluctuating velocity component. The findings showed a new implementation of a triple decomposition technique to instationary air–water flows.
Keyword Instationary air-water flows
Flow instabilities
Phase-detection probe
Signal processing
Triple decomposition
Pooled stepped spillway
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online: 20 September 2013.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Civil Engineering Publications
Official 2014 Collection
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Citation counts: TR Web of Science Citation Count  Cited 5 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 6 times in Scopus Article | Citations
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Created: Mon, 18 Nov 2013, 17:18:10 EST by Hubert Chanson on behalf of School of Civil Engineering