Study of collisions between particles and unloaded bubbles with point-particle model embedded in the direct numerical simulation of turbulent flows

Wan, Dongdong; Yi, Xuan; Wang, Lian‐Ping; Sun, Xun; Chen, Songying; Wang, Guichao

doi:10.1016/j.mineng.2019.106137

Cited by 15 publications

(3 citation statements)

References 47 publications

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“…We furthermore note that other expressions for have been proposed in the literature (Schiller & Naumann 1933; Clift, Grace & Weber 2005; Wan et al. 2020). These are compared in Appendix C, which shows that they do not differ significantly when .…”

Section: Resultsmentioning

confidence: 66%

“…2008 a ; Fayed & Ragab 2013; Wan et al. 2020) and is additionally shown by the different mean-square fluid velocity at bubble/particle positions in figure 3( b ). To investigate this preferential concentration, we plot the norm of the rotation and strain rates of the flow at the particle/bubble positions in figure 5, with denoting an ensemble average over particles in pairs with separations smaller than .…”

Section: Resultsmentioning

confidence: 73%

“…Numerically, Wan et al. (2020) observed no reduction of the RDF, but increased relative velocities for bubble–particle pairs based on a point-particle simulation while taking gravitational effects into account. For cases without gravity, Fayed & Ragab (2013) reported and relative velocities matching those predicted by the theory of Zaichik et al.…”

Section: Theoretical Background and Existing Modelsmentioning

confidence: 99%

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Bubble–particle collisions in turbulence: insights from point-particle simulations

Chan

Krug

2023

J. Fluid Mech.

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Bubble–particle collisions in turbulence are central to a variety of processes such as froth flotation. Despite their importance, details of the collision process have not received much attention yet. This is compounded by the sometimes counter-intuitive behaviour of bubbles and particles in turbulence, as exemplified by the fact that they segregate in space. Although bubble–particle relative behaviour is fundamentally different from that of identical particles, the existing theoretical models are nearly all extensions of theories for particle–particle collisions in turbulence. The adequacy of these theories has yet to be assessed as appropriate data remain scarce to date. In this investigation, we study the geometric collision rate by means of direct numerical simulations of bubble–particle collisions in homogeneous isotropic turbulence using the point-particle approach over a range of the relevant parameters, including the Stokes and Reynolds numbers. We analyse the spatial distribution of bubble and particles, and quantify to what extent their segregation reduces the collision rate. This effect is countered by increased approach velocities for bubble–particle compared to monodisperse pairs, which we relate to the difference in how bubbles and particles respond to fluid accelerations. We found that in the investigated parameter range, these collision statistics are not altered significantly by the inclusion of a lift force or different drag parametrisations, or when assuming infinite particle density. Furthermore, we critically examine existing models and discuss inconsistencies therein that contribute to the discrepancy.

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Section: Resultsmentioning

confidence: 66%