Asymmetry and penetration of transitional plane fountains in stratified fluid

Abstract

Fountains injected into stratified fluids are widely found in environmental and industrial settings. The onset of asymmetry and entrainment that occurs in transitional fountains is the key to understanding turbulence generation and entrainment mechanisms in fountains. In addition to the Reynolds number (Re) and the Froude number (F r), the

Correlations for maximum penetration heights of transitional plane fountains in linearly stratified fluids

“…This paper is a continuation of our recent study [1] in which the asymmetric transition and the maximum fountain penetration heights of transitional plane fountains in linearly stratified 1 Corresponding author: Email: wenxian.lin@jcu.edu.au, Phone: +61-7-4781-5091, Fax: +61-7-4781-6788 (W. Lin) fluids were investigated using a series of three-dimensional direct numerical simulations (DNS) obtained by ANSYS Fluent over the ranges of 25 ≤ Re ≤ 300 and 0 ≤ s ≤ 0.5, all at F r = 10. The Reynolds number, Re, the Froude number, F r, and the dimensionless temperature stratification parameter, s, which are the major governing parameters for fountains in linearly stratified fluids, are defined as follows,…”

“…It is assumed in these definitions that the density difference of the jet and the ambient fluid is due to their difference in temperatures and the Oberbeck-Boussinesq approximation is applicable. In [1], empirical correlations were developed using the numerical results to quantify the effects of Re and s on the initial and time-averaged maximum fountain penetration heights (i.e., z m,i and z m,a , respectively, which are made dimensionless by X 0 ), and the time to attain z m,i . The results show that both z m,i and z m,a increase with Re, but decrease with s, and the effect of s on z m,i and z m,a is much stronger than that of Re.…”

The structure of a turbulent line fountain

“…Stratifying the environment has been shown to reduce the rise height (Bloomfield & Kerr 1998) and to delay the onset of instabilities (Inam et al. 2015).…”

“…As a result, prior to this investigation little was known about the physical structure of the flow in three dimensions other than, as exemplified by the numerical simulations at (Inam et al. 2015), it is complex and markedly non-uniform along the span.…”

“…By contrast, at lower Froude numbers, relatively momentum-poor releases produce 'weak' fountains that display a variety of behaviours depending on the values of Fr 0 and Re 0 ≡ w 0 b 0 /ν 0 , with ν 0 the kinematic viscosity of the source fluid (Srinarayana et al 2010). Stratifying the environment has been shown to reduce the rise height (Bloomfield & Kerr 1998) and to delay the onset of instabilities (Inam et al 2015). TABLE 1.…”