The effect of microbubbles on developed turbulence

Mazzitelli, Irene; Lohse, Detlef; Toschi, Federico

doi:10.1063/1.1528619

Cited by 106 publications

(122 citation statements)

References 29 publications

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“…that are randomly distributed. This is clearly not the case in turbulent bubbly flows, where bubbles locally accumulate in eddies, owing to inertial forces, and in particular on their downflow side, mainly owing to the lift force [8,9,17]. The deviation from the analytical theory can thus be attributed to the relevance of inertial forces in bubble dynamics.…”

Section: Bubble Diffusionmentioning

confidence: 79%

“…In table 2 These observables indicate that, even if the turbulence intensity is rather low (i.e., β < 1), the main characteristics of bubble motion are kept, namely, sampling of high vorticity regions, of downflow zones, and reduction of the average rise velocity [9].…”

Section: Bubble Diffusionmentioning

confidence: 99%

“…K in is a subset of small wavenumbers defined according to: K in = {k such that(L 0 /(2π))k = ±(−1, 2, 2), ±(2, −1, −1) + permutations}. This type of forcing has been successfully applied in many of our previous simulations [9], [14]- [16]. Units are fixed by k min = 1 and = 1 for f b (x, t) = 0.…”

Section: Flow Simulationmentioning

confidence: 99%

“…In the present case x(x 0 , t) ∝ (0, 0, v T (t − t 0 )), with v T the bubble-rise velocity in quiescent water. The prefactor is smaller than 1 as the turbulent fluctuations reduce the average bubble-rise velocity [8,9]. Thus, defining…”

Section: Diffusion In Homogeneous and Isotropic Turbulencementioning

confidence: 99%

“…The picture that can be drawn from both experimental and numerical studies [9]- [12] is that fluid particles, in general, disperse more efficiently than heavy particles or bubbles whose diffusion is reduced by the drift along the gravity direction. Yet, a full understanding of the forces that are relevant in the phenomenon is lacking.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Lagrangian statistics for fluid particles and bubbles in turbulence

Mazzitelli

Lohse

2004

New J. Phys.

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Section: Bubble Diffusionmentioning

confidence: 79%

Section: Bubble Diffusionmentioning

confidence: 99%

Section: Flow Simulationmentioning

confidence: 99%

Section: Diffusion In Homogeneous and Isotropic Turbulencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lagrangian statistics for fluid particles and bubbles in turbulence

Mazzitelli

Lohse

2004

New J. Phys.

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Numerical investigation on effects of interphase force closures on liquid‐phase turbulence and microbubbles distribution in vertical upward channel bubbly flow

Pang

Wei

2011

Asia-Pacific J Chem Eng

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Fully understanding mechanisms of the phase distribution and modulations of bubbles on the liquid-phase turbulence is very crucial for practical applications of bubbly flows. In this paper, influences of different interphase forces on both of them were widely investigated with an Euler-Lagrange model in a vertical upward channel bubbly flow laden with microbubbles. The flow field was simulated by using direct numerical simulations (DNS), while the bubble dynamics were fully analyzed by integration of Newtonian equations of motion taking into account of four different combinations of interphase forces. The phase distribution and turbulence statistics of the liquid phase were comprehensively analyzed for all testing cases. The results show that the local void fraction profiles for different testing cases are different, whereas profiles of the turbulent statistics for all cases have a similar distributing trend with different magnitudes. It can be concluded from the present results that the drag force, the lift force, and the added mass force have a comparatively important influence on the local void fraction profile and the liquid-phase turbulence. In contrast, the influence of the pressure gradient force seems to be extremely small. 

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Numerical studies on effects of bubbles regular array on the liquid‐phase turbulence

Pang

Wei

2010

Can J Chem Eng

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It is well known that additive drag-reducing methods have broadly developing prospects, so studies on mechanisms of additive drag reduction are very necessary. We hypothesised that the main reason for bubbles induced drag reduction is the modification on liquid-phase turbulence structure by the addition of bubbles, and therefore such modification is the focus of our investigation. In this paper, effects of bubbles on liquid-phase turbulence under the circumstance of regular bubble array were investigated by using Euler-Lagrange two-way numerical simulations. The liquid-phase velocity field was solved by using direct numerical simulations (DNS) in Euler frame of reference, and the bubble motion was tracked by using Newtonian motion equations that took into account interaction forces including drag force, shear lift force, gravity force, buoyant force, and inertia force in Lagrange frame of reference. The coupling between the phases was realised by regarding the interphase forces as momentum source terms of the continuous phase. Similarities and differences for effects of bubbles and surfactants on liquid turbulent flows were also analysed. The study indicated that addition of bubbles enhances the mean streamwise velocity, greatly reduces the Reynolds stress, and shows anisotropic suppression to the velocity fluctuations. The interphase force has a great influence on budget of energy balance. It is a gain term near the wall and is a loss term in a wide range of the channel core.Il est bien connu que les méthodes de réduction de la résistance additive présentent de grandes perspectives de développement, donc lesétudes sur les mécanismes de la réduction de la résistance additive sont très nécessaires. Nous avonsélaboré comme hypothèse que la principale raison de la réduction de la résistance provoquée par les bulles est la modification de la structure de turbulence de la phase liquide par l'ajout de bulles et, par conséquent, une telle modification est le point central de notre analyse. Dans ce document, les effets des bulles sur la turbulence de la phase liquide conformémentà la circonstance de l'ensemble régulier de bulles ontété analysés en utilisant les simulations numériques bidirectionnelles d'Euler-Lagrange. La vitesse de la phase liquide aété réglée en utilisant les simulations numériques directes (DNS) dans le cadre de référence d'Euler et le mouvement des bulles aété suivi en utilisant deséquations de mouvement newtoniennes qui prenaient en compte les forces d'interaction dont la force résistante, la force de portance due au cisaillement, la force de gravité, la force de flottabilité et la force d'inertie dans le cadre de référence de Lagrange. On a réalisé le couplage entre les phases en observant les forces de l'interphase comme termes sources de la quantité de mouvement de la phase continue. On aégalement analysé les similitudes et différences pour les effets des bulles et surfactants sur lesécoulements turbulents liquides. L'étude a indiqué que l'ajout de bulles accroît la composante longitudinale de la...

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The effect of microbubbles on developed turbulence

Cited by 106 publications

References 29 publications

Lagrangian statistics for fluid particles and bubbles in turbulence

Lagrangian statistics for fluid particles and bubbles in turbulence

Numerical investigation on effects of interphase force closures on liquid‐phase turbulence and microbubbles distribution in vertical upward channel bubbly flow

Numerical studies on effects of bubbles regular array on the liquid‐phase turbulence

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