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Scaling arguments for the fluxes in turbulent miscible fountains

Burridge, HC and Hunt, GR (2014) Scaling arguments for the fluxes in turbulent miscible fountains. Journal of Fluid Mechanics, 744. pp. 273-285. ISSN 0022-1120

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For established axisymmetric turbulent miscible Boussinesq fountains in quiescent uniform environments, expressions are developed for the fluxes of volume, momentum and buoyancy at the outflow from the fountain: the outflow referring to the counterflow at the horizontal plane of the source. The fluxes are expressed in terms of the fountain source conditions and two dimensionless functions of the source Froude number, Fr 0 : a radial function (relating a horizontal scale of the outflow to the source radius) and a volume flux function (relating the outflow and source volume fluxes). The forms taken by these two functions at low Fr 0 and high Fr 0 are deduced, thereby providing the outflow fluxes and outflow Froude number solely in terms of the source conditions. For high Fr 0 , the outflow Froude number, Fr out , is shown to be invariant, indicating (by analogy with plumes for which the 'far-field' Froude number is invariant with source Froude number) that the outflow may be regarded as 'far-field' since the fluxes within the fountain have adjusted to attain a balance which is independent of the source conditions. Based on Fr out , the fluxes in the plume that forms beyond the fountain outflow are deduced. Finally, from the results of previously published studies, we show that the scalings deduced for fountains are valid for 0.0025 ≲ Fr 0 ≲ 1.0 for low Fr 0 and Fr 0 ≳ 3.0 for high Fr 0 . © 2014 Cambridge University Press.

Item Type: Article
Divisions: Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:16
Last Modified: 23 Nov 2017 04:04