Entrainment by turbulent fountains

Abstract

Experimental measurements of entrainment by turbulent fountains from circular sources in quiescent uniform environments are presented. Our results span almost four orders of magnitude in the source Froude number (0.004 Fr 0 25) and thereby encompass the entrainment across all classes of fountain behaviour identified to date. We identify scalings for the entrained volume flux Q E , in terms of Fr 0 and the source volume flux Q 0 , within a number of distinct Froude number bands corresponding to each class of fountain. Additionally we identify a distinct class of new behaviour, as yet unreported, for Fr 0 0.1.

Entrainment and structure of negatively buoyant jets

“…In addition to rise height, it is also useful to be able to measure and predict overall entrainment and dilution in fountains, which is of significant importance to the application of brine discharge in desalination plants, where dilution levels are crucial to mitigating ecosystem damage (Pincince & List 1973). Burridge & Hunt (2016) took bulk measurements of the total entrained volume flux of fountains with different , finding different scaling relations across the various classifications. Kaminski, Tait & Carazzo (2005) also used bulk measurements to investigate entrainment, but specific for the initial rise stage, where they found evidence that entrainment may be significantly reduced in negatively buoyant jets compared to neutral jets.…”

Experiments on the sedimentation front in steady particle-driven gravity currents

“…In panel (a) we show how the total volume flux entrained into a single-phase fountain is measured in a large tank of width and depth 45 cm. This investigation follows the process employed by Burridge & Hunt (2016). The fountain source is elevated and the dense fountain liquid accumulates at the bottom of the tank.…”

“…appendix A), so that the fountain behaves as an analogous single-phase fountain (Mingotti & Woods 2016). We employ an empirical correlation developed through careful experiments by Burridge & Hunt (2016) to estimate the entrainment into the fountain based on the Froude number, leading to the estimate for the volume flux feeding the gravity current…”

Surface expression of a wall fountain: application to subglacial discharge plumes

“…Many of the previous studies have examined the entrainment of ambient fluid into an axisymmetric fountain (e.g. Burridge and Hunt, 2016;Bloomfield and Kerr, 1998). Although turbulent fountains and turbulent plumes are governed by approximately the same force balance, entrainment into fountains is significantly more complex due to the potential reentrainment of sinking fluid into the rising fountain.…”