High-Speed Imaging of Drops and Bubbles

Thoroddsen, Sigurður T.; Etoh, T. G.; Takehara, Kohsei

doi:10.1146/annurev.fluid.40.111406.102215

Cited by 353 publications

(215 citation statements)

References 133 publications

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“…52 For perspective, herein we use between 160 and 288 Mpx of image information to calculate each velocity volume, i.e. 4 Mpx/frame; 4 cameras; 5-9 volumes; for 2 laser pulses.…”

Section: B Future Directionsmentioning

confidence: 99%

Scanning tomographic particle image velocimetry applied to a turbulent jet

2013

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We introduce a modified tomographic PIV technique using four high-speed video cameras and a scanning pulsed laser-volume. By rapidly illuminating adjacent subvolumes onto separate video frames, we can resolve a larger total volume of velocity vectors, while retaining good spatial resolution. We demonstrate this technique by performing time-resolved measurements of the turbulent structure of a round jet, using up to 9 adjacent volume slices. In essence this technique resolves more velocity planes in the depth direction by maintaining optimal particle image density and limiting the number of ghost particles. The total measurement volumes contain between 1 ×106 and 3 ×106 velocity vectors calculated from up to 1500 reconstructed depthwise image planes, showing time-resolved evolution of the large-scale vortical structures for a turbulent jet of Re up to 10 000.

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“…52 For perspective, herein we use between 160 and 288 Mpx of image information to calculate each velocity volume, i.e. 4 Mpx/frame; 4 cameras; 5-9 volumes; for 2 laser pulses.…”

Section: B Future Directionsmentioning

confidence: 99%

Scanning tomographic particle image velocimetry applied to a turbulent jet

2013

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“…Investigation of drop impact started more than a century ago with the experimental studies of Worthington using pioneering photography techniques at the end of the 19th century (Worthington 1876). Since then, drop impact has been an intensive subject of research particularly in these past twenty years thanks to the parallel improvement of both high speed imagery (Thoroddsen et al 2008) and numerical simulations (Fuster et al 2009;Agbaglah et al 2011). However, despite these numerous works, a full understanding of droplet impact dynamics is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Two mechanisms of droplet splashing on a solid substrate

et al. 2017

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We investigate droplet impact on a solid substrate in order to understand the influence of the gas in the splashing dynamics. We use numerical simulations where both the liquid and the gas phases are considered incompressible in order to focus on the gas inertial and viscous contributions. We first confirm that the dominant gas effect on the dynamics is due to its viscosity through the cushioning of the gas layer beneath the droplet. We then exhibit an additional inertial effect that is directly related to the gas density. The two different splashing mechanisms initially suggested theoretically are observed numerically, depending on whether a jet is created before or after the impacting droplet wets the substrate. Finally, we provide a phase diagram of the drop impact outputs as the gas viscosity and density vary, emphasizing the dominant effect of the gas viscosity with a small correction due to the gas density. Our results also suggest that gas inertia influences the splashing formation through a Kelvin-Helmoltz like instability of the surface of the impacting droplet, in agreement with former theoretical works.

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“…The investigations use digital high speed cameras to obtain a high spatial and temporal resolution. The use of high speed imaging is necessary because the interesting time scales lie in the order of microseconds and even below [12]. The analysis of the generated data is a crucial aspect especially for serial examinations which are necessary for randomly distributed events like coalescence.…”

Section: Introductionmentioning

confidence: 99%

Automated image analysis for trajectory determination of single drop collisions

Kamp

Hänsch

Kendzierski

et al. 2016

Computers & Chemical Engineering

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The fundamental analysis of drop coalescence probability in liquid/liquid systems is necessary to reliably predict drop size distributions in technical applications. For this crucial investigation two colliding oil drops in continuous water phase were recorded with different high speed camera set-ups under varying conditions. In order to analyse the huge amount of recorded image sequences with varying resolutions and qualities, a robust automated image analysis was developed. This analysis is able to determine the trajectories of two colliding drops as well as the important events of drop detachment from cannulas and their collision. With this information the drop velocity in each sequence is calculated and mean values of multiple drop collisions are determined for serial examinations of single drop collisions. Using the developed automated image analysis for drop trajectory and velocity calculation, approximately 1-2 recorded high speed image sequences can be evaluated per minute.

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High-Speed Imaging of Drops and Bubbles

Cited by 353 publications

References 133 publications

Scanning tomographic particle image velocimetry applied to a turbulent jet

Scanning tomographic particle image velocimetry applied to a turbulent jet

Two mechanisms of droplet splashing on a solid substrate

Automated image analysis for trajectory determination of single drop collisions

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