Bubble-laden thermals in supersaturated water

Peñas, Pablo; Enríquez, Óscar R.; Rodríguez-Rodríguez, Javier

doi:10.1017/jfm.2021.655

Cited by 2 publications

(1 citation statement)

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“…Entrainment is actually key to modelling numerous structures like gravity currents [15,16], wildfire plumes [18], moist convection cells [19] or heat plumes in ventilated spaces [20]. By a simple modelling of entrainment through a single scalar coefficient, Morton et al [21] developed in 1956 the turbulent thermal model, which has proved a successful model of finite releases of buoyant fluid in a multitude of contexts [22], even for finite buoyant releases made of immiscible fluid [23] and bubbles [24] generated from different initial conditions. Similarly, past experiments on finite releases of heavy particles have shown that after an initial regime of acceleration, the dynamics of such clouds can be described with the turbulent thermal model [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Effects of particle size and background rotation on the settling of particle clouds

Kriaa,

Subra,

Favier

et al. 2023

Preprint

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We experimentally investigate the behaviour of instantaneous localised releases of heavy particles falling as turbulent clouds in quiescent water, both with and without background rotation. We present the results of 514 systematic experiments for no rotation and for three rotation rates Ω = 5, 10, 20rpm, and for the size of particles in the range 5µm to 1mm, exploring four decades of the Rouse number R ∈ [6 × 10 −4 , 4] which quantifies the inertia of particles. In the canonical framework of turbulent thermals described by Morton et al., [Proc. R. Soc. A: Math. Phys. Sci. 234, 1 (1956)], we compare particle clouds with salt-water thermals to highlight specificities due to the particulate nature of the turbulence forcing. In the absence of rotation, particle clouds initially behave as salty thermals with a modulation of their entrainment capacity, which is optimally enhanced for a finite inertia R 0.3 due to particulate effects. However this regime of turbulence is limited in time due to the inertial decoupling between turbulent eddies and particles. For the three values of Ω explored here, the particulate enhancement of entrainment is inhibited. Moreover the cloud's expansion is interrupted when the Coriolis force overcomes its inertia, forcing the cloud to transform into vortical columnar flows which considerably increase the residence time of particles.

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