Characteristics of low Reynolds number non-Boussinesq fountains from non-circular sources

Vinoth, B. R.; Panigrahi, Pradipta Kumar

doi:10.1063/1.4862443

Cited by 13 publications

(8 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a common feature of elongated fountains (i.e. H m b i ), for which a radius-independent 'bobbing' behaviour is observed (see Vinoth & Panigrahi 2014).…”

Section: Fountain Fluctuationsmentioning

confidence: 94%

Experimental non-Boussinesq fountains

2015

View full text Add to dashboard Cite

International audienceLaboratory experiments involving downward air-helium fountains are presented. The large density differences between these releases and the ambient allow us to investigate how non-Boussinesq effects modify fountain heights and fountain fluctuations in comparison with the Boussinesq case (i.e. marginal density differences). In these experiments, the source Froude number is varied over a wide range covering (i) the very weak, (ii) the weak and (iii) the forced fountain regimes. It is shown that the classical Boussinesq correlations can be extended to the non-Boussinesq case provided that the Froude number is multiplied by the square root of the ratio between the released fluid density and that of the ambient. In the range investigated, no influence of the source Reynolds number is observed

show abstract

“…This is a common feature of elongated fountains (i.e. H m b i ), for which a radius-independent 'bobbing' behaviour is observed (see Vinoth & Panigrahi 2014).…”

Section: Fountain Fluctuationsmentioning

confidence: 94%

Experimental non-Boussinesq fountains

2015

View full text Add to dashboard Cite

show abstract

“…Although studies on fountains commenced in the 1950s (see, e.g., [1]), they are still being extensively investigated (see, e.g., [2][3][4][5][6][7][8][9][10][11][12]). However, the studies have focused on round fountains, which may be either 'very weak' when F r 1, or 'weak' when 1 F r 3, or 'forced' when F r 3, as classified by Kaye and Hunt [13] and Burridge and Hunt [7].…”

Section: Introductionmentioning

confidence: 99%

Asymmetry and penetration of transitional plane fountains in stratified fluid

Inam

Lin

Armfield

2015

International Journal of Heat and Mass Transfer

View full text Add to dashboard Cite

show abstract

“…It is therefore not surprising that their rise heights scale differently. Likewise, experiments on rectangular sources by Vinoth & Panigrahi (2014) have shown that large source ratios are required at the source to attain the two-dimensional scaling. In our experiments, it is questionable whether the upflowing core, which remains slender (e.g.…”

Section: Rise Heights and Lateral Excursionsmentioning

confidence: 99%

“…There are many techniques available to extract temporal information from a series of snapshots or signals. Decomposition methods, for instance, have successfully separated different oscillating modes in low-Re 0 fountains in Vinoth & Panigrahi (2014). Burridge & Hunt (2013), in their study of fluctuations at the (unconfined) fountain top, performed Fourier transforms of the rise height signal z f (t) to identify dominant frequencies.…”

Section: Frequenciesmentioning

confidence: 99%

The influence of spanwise confinement on round fountains

Debugne

Hunt

2018

J. Fluid Mech.

View full text Add to dashboard Cite

We study experimentally the effects of spanwise confinement on turbulent miscible fountains issuing from a round source of radius $r_{0}$. A dense saline solution is ejected vertically upwards into a fresh-water environment between two parallel plates, separated by a gap of width $W$, which provide restraint in the spanwise direction. The resulting fountain, if sufficiently forced, rapidly attaches to the side plates as it rises and is therefore ‘confined’. We report on experiments for five confinement ratios $W/r_{0}$, spanning from strongly confined ($W/r_{0}\rightarrow 2$) to weakly confined ($W/r_{0}\approx 24$), and for source Froude numbers $Fr_{0}$ ranging between $0.5\leqslant Fr_{0}\leqslant 96$. Four distinct flow regimes are observed across which the relative importance of confinement, as manifested by the formation and growth of quasi-two-dimensional structures, varies. The onset of each regime is established as a function of both $W/r_{0}$ and $Fr_{0}$. From our analysis of the time-averaged rise heights, we introduce a ‘confined’ Froude number $Fr_{c}\equiv Fr_{0}(W/r_{0})^{-5/4}$, which encompasses the effects of confinement and acts as the governing parameter for confined fountains. First-order statistics extracted from the flow visualisation, such as the time-averaged rise height and lateral excursions, lend further insight into the flow and support the proposed classification into regimes. For highly confined fountains, the flow becomes quasi-two-dimensional and, akin to quasi-two-dimensional jets and plumes, flaps (or meanders). The characteristic frequency of this flapping motion, identified through an ‘eddy counting’ approach, is non-dimensionalised to a Strouhal number of $St=0.12{-}0.16$, consistent with frequencies found in quasi-two-dimensional jets and plumes.

show abstract

Characteristics of low Reynolds number non-Boussinesq fountains from non-circular sources

Cited by 13 publications

References 51 publications

Experimental non-Boussinesq fountains

Experimental non-Boussinesq fountains

Asymmetry and penetration of transitional plane fountains in stratified fluid

The influence of spanwise confinement on round fountains

Contact Info

Product

Resources

About