Drag and lift forces on microscopic bubbles entrained by a vortex

Sridhar, Ganiga Srinivasaiah; Katz, Joseph

doi:10.1063/1.868637

Cited by 196 publications

(173 citation statements)

References 16 publications

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“…It can be utilized in various engineering contexts such as the control of chemical reactions and heat transfer. Yet, there are only few studies on the interaction between a vortex ring and bubbles, besides the experimental works of Sridhar-Katz [11,12] and no attempts have been made to apply this approach to bubble motion control.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Entrainment and Transport of Gas Bubbles by a Vortex Ring

Uchiyama¹,

Yoshii²

2015

J Chem Eng Process Technol

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The control of the motion of small gas bubbles by a vortex ring is explored through numerical simulation. Hydrogen bubbles with a diameter of 0.2 mm are arranged in quiescent water, forming a bubble cluster. A vortex ring is launched vertically, passing through the bubble cluster. The behaviors of the vortex ring and bubble motion are analyzed. The diameter of the vortex ring at launch is 42.5 mm, and the bubble volume fraction is less than 0.04. As the vortex ring convects through the bubble cluster, it displaces and entrains the bubbles. After the vortex ring passes through the cluster, the bubbles are involved in the vortex ring. The research also clarifies the evolution of the diameter and circulation of the vortex ring.

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Section: Introductionmentioning

confidence: 99%

Numerical Study of the Entrainment and Transport of Gas Bubbles by a Vortex Ring

Uchiyama¹,

Yoshii²

2015

J Chem Eng Process Technol

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“…Note that, however, other expressions that suppose a stronger lift action and a different dependence on the local vorticity have also been proposed. 30 Simulation of the flow. Direct numerical simulation is employed in order to simulate the velocity field u(x,t).…”

mentioning

confidence: 99%

The effect of microbubbles on developed turbulence

2003

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The motion and the action of microbubbles in homogeneous and isotropic turbulence are investigated through (three-dimensional) direct numerical simulations of the Navier–Stokes equations and applying the Lagrangian approach to track the bubble trajectories. The forces acting on the bubbles are added mass, drag, lift, and gravity. The bubbles are found to accumulate in vortices, preferably on the side with downward velocity. This effect, mainly caused by the lift force, leads to a reduced average bubble rise velocity. Once the reaction of the bubbles on the carrier flow is embodied using a point-force approximation, an attenuation of the turbulence on large scales and an extra forcing on small scales is found.

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“…However, the presence of a wall and its associated velocity gradients can be expected to introduce steady errors (bias or fixed), which vary spatially relative to the surface. Sridhar and Katz (1995) measured forces acting on bubbles as they are entrained by a vortex. They used triple-exposure PIV, thereby giving velocity and acceleration of the fluid and bubbles simultaneously.…”

Section: Analysesmentioning

confidence: 99%

“…For their liquid flow, Soranna et al (2006) cite Sridhar and Katz (1995) in indicating that slip between their particles and fluid would have been less than 0.2%.…”

Section: Particle Motionmentioning

confidence: 99%

Estimated Uncertainties in the Idaho National Laboratory Matched-Index-of-Refraction Lower Plenum Experiment

McEligot¹,

McIlroy²,

Johnson³

2007

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The purpose of the fluid dynamics experiments in the MIR (Matched-Index-of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for typical Very High Temperature Reactor (VHTR) plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. The experiments use optical techniques, primarily particle image velocimetry (PIV) in the INL MIR flow system. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The objective of the present report is to develop understanding of the magnitudes of experimental uncertainties in the results to be obtained in such experiments. Unheated MIR experiments are first steps when the geometry is complicated. One does not want to use a computational technique, which will not even handle constant properties properly. This report addresses the general background, requirements for benchmark databases, estimation of experimental uncertainties in mean velocities and turbulence quantities, the MIR experiment, PIV uncertainties, positioning uncertainties, and other contributing measurement uncertainties.The accuracy of the velocity field determination is ultimately limited by the ability of the scattering particles to follow the unsteady motion of the continuous phase. For the particles in the MIR VHTR experiment, the estimated cutoff frequency is about 40 kHz. The frequency of shedding from the posts in the MIR model is estimated to be of the order of 1 Hz and, therefore, the particles should follow the flow.Based on review of the literature, we estimate that the random uncertainty in measured particle displacement for our system and experiment is about 0.3 pixel for a single realization away from the walls. As an example, we estimated the uncertainties in measurements for the maximum velocity in an inlet jet flow operating at about its minimum flow rate. Consequently, this example would provide worst-case estimates in some senses. For the uncertainty in the mean velocity at this location, one could report With the current MIR model and the 3D PIV system, McIlroy and colleagues examined the effects of sample size for a typical set of measurements. Trends were generally as observed by Uzol and Camci. Preliminary conclusions were that (for this view and processing parameters) about 750 images should be collected to reduce the scatter in mean velocity statistics to between 0.4 and 10% v for velocities greater than about 2 m/s. The trends predicted by an uncertainty analysis are consistent with the observations, but, for the most part, the expected values are less than the scatter observed. Preliminary conclusions from the comparisons are that (1) more samples should be collected than predict...

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Drag and lift forces on microscopic bubbles entrained by a vortex

Cited by 196 publications

References 16 publications

Numerical Study of the Entrainment and Transport of Gas Bubbles by a Vortex Ring

Numerical Study of the Entrainment and Transport of Gas Bubbles by a Vortex Ring

The effect of microbubbles on developed turbulence

Estimated Uncertainties in the Idaho National Laboratory Matched-Index-of-Refraction Lower Plenum Experiment

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