Optical observation of convective flow patterns in liquid helium

1996 ◽  
Vol 46 (S1) ◽  
pp. 85-86 ◽  
Author(s):  
Adam L. Woodcraft ◽  
Peter G. J. Lucas ◽  
Richard G. Matley ◽  
William Y. T. Wong
Keyword(s):  
Liquid Helium ◽  
Convective Flow ◽  
Flow Patterns ◽  
Optical Observation

Recognition and tracking of convective flow patterns using Wollaston shearing interferometry

2017 ◽  
Vol 60 (6) ◽  
pp. 1327-1344 ◽  
Author(s):  
F. Zaussinger ◽  
A. Krebs ◽  
V. Travnikov ◽  
Ch. Egbers
Keyword(s):  
Convective Flow ◽  
Flow Patterns ◽  
Shearing Interferometry

Impact of fracture network geometry on free convective flow patterns

2014 ◽  
Vol 71 ◽  
pp. 65-80 ◽  
Author(s):  
Katharina Vujević ◽  
Thomas Graf ◽  
Craig T. Simmons ◽  
Adrian D. Werner
Keyword(s):  
Convective Flow ◽  
Fracture Network ◽  
Flow Patterns ◽  
Free Convective Flow ◽  
Network Geometry

scholarly journals Observations of plasma vortices in the vicinity of flow-braking: a case study

2009 ◽  
Vol 27 (8) ◽  
pp. 3009-3017 ◽  
Author(s):  
K. Keika ◽  
R. Nakamura ◽  
M. Volwerk ◽  
V. Angelopoulos ◽  
W. Baumjohann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Convective Flow ◽  
Flow Patterns ◽  
Plasma Flows ◽  
Convective Flows ◽  
Field Fluctuations ◽  
Plasma Vortices

Abstract. We examine fast plasma flows and magnetic field fluctuations observed by THEMIS at 03:00–03:30 UT on 12 December 2007. All THEMIS probes are situated in the near-Earth plasma sheet (XSM>−10 RE) with 1–2 RE spacecraft separations in azimuthal and radial directions. We focus on the observations of plasma convective flows made simultaneously by more than one THEMIS probe. At about 03:10 UT and 03:14 UT, the THEMIS P2 probe observed earthward flows of >100 km/s. The THEMIS P1 probe, located duskward and earthward of P2, observed tailward flows under a positive Bz. The inner most probe THEMIS P4, located at almost the same MLT as THEMIS P1 and P2, did not see any clear flow. We examine the convective flow patterns for the THEMIS observations. We conclude that plasma vortices are formed near the region where the earthward flows slow down and turn in azimuthal directions.

Acinar flow irreversibility caused by perturbations in reversible alveolar wall motion

1999 ◽  
Vol 86 (3) ◽  
pp. 977-984 ◽  
Author(s):  
Akira Tsuda ◽  
Yoshio Otani ◽  
James P. Butler
Keyword(s):  
Convective Flow ◽  
Large Scale ◽  
Wall Motion ◽  
Silicone Oil ◽  
Flow Patterns ◽  
Small Degree ◽  
Alveolar Wall ◽  
Boundary Motion ◽  
Convective Mixing ◽  
Ultrafine Aerosol

Mixing associated with “stretch-and-fold” convective flow patterns has recently been demonstrated to play a potentially important role in aerosol transport and deposition deep in the lung (J. P. Butler and A. Tsuda. J. Appl. Physiol. 83: 800–809, 1997), but the origin of this potent mechanism is not well characterized. In this study we hypothesized that even a small degree of asynchrony in otherwise reversible alveolar wall motion is sufficient to cause flow irreversibility and stretch-and-fold convective mixing. We tested this hypothesis using a large-scale acinar model consisting of a T-shaped junction of three short, straight, square ducts. The model was filled with silicone oil, and alveolar wall motion was simulated by pistons in two of the ducts. The pistons were driven to generate a low-Reynolds-number cyclic flow with a small amount of asynchrony in boundary motion adjusted to match the degree of geometric (as distinguished from pressure-volume) hysteresis found in rabbit lungs (H. Miki, J. P. Butler, R. A. Rogers, and J. Lehr. J. Appl. Physiol. 75: 1630–1636, 1993). Tracer dye was introduced into the system, and its motion was monitored. The results showed that even a slight asynchrony in boundary motion leads to flow irreversibility with complicated swirling tracer patterns. Importantly, the kinematic irreversibility resulted in stretching of the tracer with narrowing of the separation between adjacent tracer lines, and when the cycle-by-cycle narrowing of lateral distance reached the slowly growing diffusion distance of the tracer, mixing abruptly took place. This coupling of evolving convective flow patterns with diffusion is the essence of the stretch-and-fold mechanism. We conclude that even a small degree of boundary asynchrony can give rise to stretch-and-fold convective mixing, thereby leading to transport and deposition of fine and ultrafine aerosol particles deep in the lung.

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