Line fountain behavior at low-Reynolds number

Srinarayana, N.; Williamson, N.; Armfield, S.W.; Lin, Wenxian

doi:10.1016/j.ijheatmasstransfer.2009.12.048

Cited by 19 publications

(20 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fountains issuing from high-aspect-ratio rectangular sources have been studied experimentally by Zhang & Baddour (1997) and Srinarayana et al. (2010). Experiments have also been conducted on linear arrays of closely spaced circular sources as approximations to such high-aspect-ratio rectangular sources (Baines, Turner & Campbell 1990; Bloomfield & Kerr 1998).…”

Section: Introductionmentioning

confidence: 99%

The structure of a turbulent line fountain

2019

View full text Add to dashboard Cite

Line fountains form when heavy miscible fluid is ejected steadily upwards as a jet from a high-aspect-ratio rectangular slot, of length $L$ and half-width $b_{0}$, into lighter quiescent surroundings. Viewed along the slot from one end, previous observations reveal that the ejected fluid mixes with the environment and reaches a peak height before partially collapsing back downward under gravity to form a fountain whose top thereafter fluctuates vertically about a mean height. While the motion as perceived from this single view has provided insights that have successfully guided theoretical predictions for the initial rise height, until now a wider understanding of line fountains, and corresponding predictive capability, has been limited to this single prediction due to a lack of any other observational data. Indeed, the general behaviour of line fountains, including the structure internally and along the spanwise length $L$ of the slot, has not been reported previously. To address this, flow visualisations and comprehensive measurements of saline fountains in an aqueous environment are presented here that reveal their complex overall structure and behaviours. After establishing the uniformity of the source conditions from slots of aspect ratio $600:1$ and $300:1$, we first show that double-averaged (spanwise and time) rise heights $\overline{\overline{z}}_{v}/b_{0}$ scale on $Fr_{0}^{4/3}$, $Fr_{0}$ being the source Froude number, with vertical fluctuations being circa 20 % of these heights. Then, simultaneously interrogating the flow as viewed from above and from the side onto the spanwise dimension, we identify three distinct patterns of behaviour. Instrumental to distinguishing these behaviours were the contrasting signatures we observed in the time series of rise height departures from the mean which led us to the following classification: (i) non-uniform flapping for $0.05\lesssim \overline{\overline{z}}_{v}/L\lesssim 0.30$, in which the lateral motion of the fountain takes the form of an oscillatory wave with a wavelength of $2L/3$ (approx.); (ii) uniform flapping for $0.30\lesssim \overline{\overline{z}}_{v}/L\lesssim 0.45$, in which the entire fountain sways to the left and then to the right side of the slot; and (iii) disorganised flapping for $\overline{\overline{z}}_{v}/L\gtrsim 0.45$. Regarding the internal structure, we show that unlike a classic round fountain, eddying structures comparable in scale with the rise height form towards the top of the fountain, and the counterflow forms predominantly to one side of the jet. We then identify the single dominant mechanism driving the flapping motions, successfully linking the wave-like behaviour observed along the span to the internal structure and vertical oscillations. Quantifying the oscillatory motions, both the vertical and flapping frequencies scale as $Fr_{0}^{-2}$, and we demonstrate and explain a robust coupling between these frequencies that follows a ratio of 2:1.

show abstract

Section: Introductionmentioning

confidence: 99%

The structure of a turbulent line fountain

2019

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…Ansong et al [6] classified the fluid motion around the interface of a density-stratified fluid when a jet penetrated the interface and further theoretically examined jet height, comparing the corresponding measurements. Papanicolaou and Stamoulis [7] and Srinarayana et al [8] independently investigated the distance of a jet issued vertically downward from a nozzle mounted above a density-stratified fluid by their experimental works. Baddour et al [9] measured the height of a jet issued from a tank bottom and clarified that the Boussinesq approximation was applicable to predict the height only when the density ratio of the jet to the ambient fluid was low.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Behavior of a Jet Issued into Two-Layer Density-Stratified Fluid

Shakouchi¹,

Fukue²,

Uchiyama

2015

JFCMV

View full text Add to dashboard Cite

This study experimentally investigates a jet flow issued into a two-layer density-stratified fluid in a tank and the resultant mixing phenomena. The upper and lower fluids are water and a NaClwater solution, respectively, with the lower fluid issued vertically upward from a circular nozzle mounted on the tank bottom. Experimental highlights of the jet behavior and mixing phenomena are classified into three patterns according to the jet Reynolds number and mass concentration of the NaCl-water solution. The internal density current clearly occurs along the density interface, and the maximum jet height is predicted by the Froude number defined by the density difference between the upper and lower fluids. The effect of fluid thickness on the maximum jet height is also clarified.

show abstract

Line fountain behavior at low-Reynolds number

Cited by 19 publications

References 26 publications

The structure of a turbulent line fountain

The structure of a turbulent line fountain

Asymmetry and penetration of transitional plane fountains in stratified fluid

Investigation of the Behavior of a Jet Issued into Two-Layer Density-Stratified Fluid

Contact Info

Product

Resources

About