μ-PIV measurements of the ensemble flow fields surrounding a migrating semi-infinite bubble

Yamaguchi, Eiichiro; Smith, Bradford J.; Gaver, Donald P.

doi:10.1007/s00348-009-0662-1

Cited by 17 publications

(23 citation statements)

References 49 publications

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“…No interface can be seen, while it is also clear that the two cameras have different spatial resolution. Interface reconstruction in two-phase systems from µPIV images has been discussed by Yamaguchi et al (2009). Generally the interface is reconstructed based on the presence of particles in one region.…”

Section: Two-colour µPiv Data Treatmentmentioning

confidence: 99%

Studies of plug formation in microchannel liquid–liquid flows using advanced particle image velocimetry techniques

Chinaud

Roumpea

Angeli

2015

Experimental Thermal and Fluid Science

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Please cite this article as: C. Maxime, R. Eyangelia-Panagiota, A. Panagiota, Studies of plug formation in microchannel liquid-liquid flows using advanced particle image velocimetry techniques, Experimental Thermal and Fluid Science (2015), doi: http://dx. AbstractTwo complementary micro Particle Image Velocimetry (µPIV) techniques have been developed in this work to study plug formation at a microchannel inlet during the flow of two immiscible liquids. Experiments were conducted for different fluid flow rate combinations in a T-junction, where all branches had internal diameters equal to 200 µm. The dispersed phase was a water/glycerol solution and was injected from the side branch of the junction, while the continuous phase was silicon oil and was injected along the main channel axis. In the twocolour µPIV technique two laser wavelengths are used to illuminate two different tracer particles, one in each fluid, and phase averaged velocity profiles can be obtained in both phases simultaneously. In the high speed bright field µPIV technique, a backlight illuminates the test section, where the dispersed phase plug is seeded with tracer particles. This approach allows velocity profiles of the forming dispersed plugs to be followed in time.Non-dimensional plug lengths were found to vary linearly with the aqueous to organic phase flow rate ratio, in agreement with a well-known scaling correlation. The flowrate ratio also affected the velocity profiles within the forming plugs. In particular, for a ratio equal to one, a vortex appears at the tip of the plug in the early stages of plug formation. The interface curvature at the rear of the forming plug changes sign at the later stages of plug formation and accelerates the thinning of the meniscus leading to plug breakage. The spatially resolved velocity fields obtained in both phases with the two-colour PIV show that the continuous phase resists the flow of the dispersed phase into the main channel at the rear of the plug meniscus and causes the change in the interface curvature. This change of interface curvature was accompanied by an increase in vorticity inside the dispersed phase during plug formation.

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Section: Two-colour µPiv Data Treatmentmentioning

confidence: 99%

Studies of plug formation in microchannel liquid–liquid flows using advanced particle image velocimetry techniques

Chinaud

Roumpea

Angeli

2015

Experimental Thermal and Fluid Science

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“…In μ-PIV volumetric laser illumination is used: the shallow focal depth of the microscope objective lens yields a pseudo-two-dimensional plane of focused particles for correlation (Santiago et al 1998). The pulsatile bubble propagation velocity fields analysed herein are measured with the μ-PIV techniques described extensively in Yamaguchi, Smith & Gaver (2009), and post-processed as described in Smith, Yamaguchi & Gaver (2010).…”

Section: Methods – Experimental Datamentioning

confidence: 99%

Lagrangian transport properties of pulmonary interfacial flows

Smith

Lukens²,

Yamaguchi³

et al. 2011

J. Fluid Mech.

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Disease states characterized by airway fluid occlusion and pulmonary surfactant insufficiency, such as respiratory distress syndrome, have a high mortality rate. Understanding the mechanics of airway reopening, particularly involving surfactant transport, may provide an avenue to increase patient survival via optimized mechanical ventilation waveforms. We model the occluded airway as a liquid-filled rigid tube with the fluid phase displaced by a finger of air that propagates with both mean and sinusoidal velocity components. Finite-time Lyapunov exponent (FTLE) fields are employed to analyse the convective transport characteristics, taking note of Lagrangian coherent structures (LCSs) and their effects on transport. The Lagrangian perspective of these techniques reveals flow characteristics that are not readily apparent by observing Eulerian measures. These analysis techniques are applied to surfactant-free velocity fields determined computationally, with the boundary element method, and measured experimentally with micro particle image velocimetry (μ-PIV). We find that the LCS divides the fluid into two regimes, one advected upstream (into the thin residual film) and the other downstream ahead of the advancing bubble. At higher oscillatory frequencies particles originating immediately inside the LCS experience long residence times at the air–liquid interface, which may be conducive to surfactant transport. At high frequencies a well-mixed attractor region is identified; this volume of fluid cyclically travels along the interface and into the bulk fluid. The Lagrangian analysis is applied to velocity data measured with 0.01 mg ml−1 of the clinical pulmonary surfactant Infasurf in the bulk fluid, demonstrating flow field modifications with respect to the surfactant-free system that were not visible in the Eulerian frame.

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“…As such, this technique is suitable to obtain instantaneous wholefield velocity information on the micro-scale. Yamaguchi et al (2009) performed µ-PIV investigations of flow fields surrounding a steadily progressing semi-infinite bubble tip in a smoothed wall straight glass capillary having a diameter of 312 µm. They employed a computer-controlled linear actuator system to control the steady propagation of a long finger of air, and let the bubble tip pass repeatedly under the fixed microscope observation window at controlled timing.…”

Section: Flow Visualization Of Progressing Semi-infinite Bubble Tipmentioning

confidence: 99%

“…Bright spots on the fluorescent particle images on the right panels show particle flocculation indicating converging/diverging stagnation points in corresponding mean flow motions (Yamaguchi et al 2009). The experimental observations and computer simulations indicate that pulsatile bubble motion generates a non-uniform non-equilibrium LS concentration across the interface, and the resulting Marangoni stress distribution alters the bubble interface shape accordingly.…”

Section: Introductionmentioning

confidence: 99%