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A coherent synchrotron X-ray microradiology investigation of bubble and droplet coalescence.

Weon BM, Je JH, Hwu Y, Margaritondo G - J Synchrotron Radiat (2008)

Bottom Line: A quantitative application of microradiology with coherent X-rays to the real-time study of microbubble and microdroplet coalescence phenomena, with specific emphasis on the size relations in three-body events, is presented.The results illustrate the remarkable effectiveness of coherent X-ray imaging in delineating interfaces in multiphase systems, in accurately measuring their geometric properties and in monitoring their dynamics.

View Article: PubMed Central - HTML - PubMed

Affiliation: X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.

ABSTRACT
A quantitative application of microradiology with coherent X-rays to the real-time study of microbubble and microdroplet coalescence phenomena, with specific emphasis on the size relations in three-body events, is presented. The results illustrate the remarkable effectiveness of coherent X-ray imaging in delineating interfaces in multiphase systems, in accurately measuring their geometric properties and in monitoring their dynamics.

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Sequential images of coalescence events taken in real time using synchrotron X-ray microradiography: (a) two coalescing air microbubbles at the water–oil interface and (b) mercury microdroplets in water.
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fig2: Sequential images of coalescence events taken in real time using synchrotron X-ray microradiography: (a) two coalescing air microbubbles at the water–oil interface and (b) mercury microdroplets in water.

Mentions: Overall, the microbubbles at our water–oil interface are similar to those in reduced gravity (Weaire, 2002 ▶; Hilgenfeldt, 2002 ▶; Divinis et al., 2004 ▶): they have almost spherical shapes, and adjacent microbubbles have point contacts rather than flat contact planes and merge into bigger microbubbles without drainage (Fig. 2a ▶). These similarities, however, are present only for sufficiently small microbubbles: specifically, near-sphericity occurs when gravitational effects are negligible with respect to the surface tension effects. This is true if B 0 → 0, where B 0 = ρD gr 2/γ is the Bond number, ρD is the water–oil density difference and g is the gravity acceleration (Aarts et al., 2005 ▶; Divinis et al., 2004 ▶). We empirically found deviations from sphericity (relative difference between the vertical and horizontal diameters) of 3–4% for bubble diameters of 400 µm and 0–1% for diameters of 100 µm. Thus, quantitative studies must be preferentially performed on microbubbles of diameter < 400 µm.


A coherent synchrotron X-ray microradiology investigation of bubble and droplet coalescence.

Weon BM, Je JH, Hwu Y, Margaritondo G - J Synchrotron Radiat (2008)

Sequential images of coalescence events taken in real time using synchrotron X-ray microradiography: (a) two coalescing air microbubbles at the water–oil interface and (b) mercury microdroplets in water.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2573953&req=5

fig2: Sequential images of coalescence events taken in real time using synchrotron X-ray microradiography: (a) two coalescing air microbubbles at the water–oil interface and (b) mercury microdroplets in water.
Mentions: Overall, the microbubbles at our water–oil interface are similar to those in reduced gravity (Weaire, 2002 ▶; Hilgenfeldt, 2002 ▶; Divinis et al., 2004 ▶): they have almost spherical shapes, and adjacent microbubbles have point contacts rather than flat contact planes and merge into bigger microbubbles without drainage (Fig. 2a ▶). These similarities, however, are present only for sufficiently small microbubbles: specifically, near-sphericity occurs when gravitational effects are negligible with respect to the surface tension effects. This is true if B 0 → 0, where B 0 = ρD gr 2/γ is the Bond number, ρD is the water–oil density difference and g is the gravity acceleration (Aarts et al., 2005 ▶; Divinis et al., 2004 ▶). We empirically found deviations from sphericity (relative difference between the vertical and horizontal diameters) of 3–4% for bubble diameters of 400 µm and 0–1% for diameters of 100 µm. Thus, quantitative studies must be preferentially performed on microbubbles of diameter < 400 µm.

Bottom Line: A quantitative application of microradiology with coherent X-rays to the real-time study of microbubble and microdroplet coalescence phenomena, with specific emphasis on the size relations in three-body events, is presented.The results illustrate the remarkable effectiveness of coherent X-ray imaging in delineating interfaces in multiphase systems, in accurately measuring their geometric properties and in monitoring their dynamics.

View Article: PubMed Central - HTML - PubMed

Affiliation: X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.

ABSTRACT
A quantitative application of microradiology with coherent X-rays to the real-time study of microbubble and microdroplet coalescence phenomena, with specific emphasis on the size relations in three-body events, is presented. The results illustrate the remarkable effectiveness of coherent X-ray imaging in delineating interfaces in multiphase systems, in accurately measuring their geometric properties and in monitoring their dynamics.

Show MeSH