scholarly journals Turbulent Vortex Ring/Free Surface Interaction

1995 ◽  
Vol 117 (3) ◽  
pp. 374-381 ◽  
Author(s):  
A. Weigand ◽  
M. Gharib

The interaction of turbulent vortex rings that approach a clean water surface under various angles is experimentally investigated. The temporal evolution of the vortex rings with an initial Reynolds number of Re0 = 7500 is characterized by the laminar/turbulent transition and asymptotic relaminarization of the flow. Using the shadowgraph technique, two major flow cases were identified as a result of the vortex-ring/free-surface interaction: a trifurcation case that results from the interaction during the transition stage, and a bifurcation case that evolves during the fully-developed turbulent stage. In contrast to the laminar interaction, the turbulent bifurcation pattern is characterized by the reconnection and mutual interaction of many small-scale structures. Simultaneous digital particle image velocimetry (DPIV) and shadowgraph measurements reveal that the evolution of the small-scale structures at the free surface is strongly dominated by the bifurcation pattern, which in turn is a consequence of the persisting laminar sublayer in the core regions of the reconnected turbulent vortex loops.

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.


2007 ◽  
Vol 3 (S247) ◽  
pp. 152-157 ◽  
Author(s):  
Oddbjørn Engvold

AbstractSeismology has become a powerful tool in studies of the magnetic structure of solar prominences and filaments. Reversely, analytical and numerical models are guided by available information about the spatial and thermodynamical structure of these enigmatic structures. The present invited paper reviews recent observational results on oscillations and waves as well as details about small-scale structures and dynamics of prominences and filaments.


2009 ◽  
Vol 399 (1) ◽  
pp. 195-208 ◽  
Author(s):  
Jacco Th. van Loon ◽  
Keith T. Smith ◽  
Iain McDonald ◽  
Peter J. Sarre ◽  
Stephen J. Fossey ◽  
...  

1999 ◽  
Vol 17 (3) ◽  
pp. 375 ◽  
Author(s):  
Y. I. Galperin ◽  
J. M. Bosqued ◽  
R. A. Kovrazhkin ◽  
A. G. Yahnin

1993 ◽  
Vol 02 (02) ◽  
pp. 183-195 ◽  
Author(s):  
M. MOHAZZAB ◽  
R. BRANDENBERGER

The formation of cusps on long cosmic strings is discussed and the probability of cusp formation is estimated. The energy distribution of the gamma-ray background due to cusp annihilation on long strings is calculated and compared to observations. Under optimistic assumptions about the cusp formation rate, we find that strings with a mass per unit length μ less than Gμ=10−14 will have an observable effect. However, it is shown that the gamma-ray bursters cannot be attributed to long ordinary strings (or loops).


2018 ◽  
Vol 68 (4-5) ◽  
pp. 509-533 ◽  
Author(s):  
Zhuo Liu ◽  
Yinglong J. Zhang ◽  
Harry V. Wang ◽  
Hai Huang ◽  
Zhengui Wang ◽  
...  

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