4D visualization study of a vortex ring life cycle using modal analyses

We consider the life cycle of an axisymmetric laminar thermal starting from the initial condition of a Gaussian buoyant blob. We find that, as time progresses, the thermal transitions through a number of distinct stages, undergoing several morphological changes before ending up as a vortex ring. Whilst each stage is interesting in its own right, one objective of this study is to set out a consistent mathematical framework under which the entire life cycle can be studied. This allows examination of the transition between the different stages, as well as shedding light on some unsolved questions from previous works. We find that the early stages of formation are key in determining the properties of the final buoyant vortex ring and that, since they occur on a time scale where viscosity has little effect, the final properties of the ring display an independence above a critical Reynolds number. We also find that rings consistently contain the same proportion of the initial heat and have a consistent vorticity flux. By considering the effect of Prandtl number, we show that thermal diffusion can have a significant impact on development, smoothing out the temperature field and inhibiting the generation of vorticity. Finally, by considering the wake left behind as well as the vortex ring that is generated, we observe that the wake can itself roll up to form a second mushroom cap and subsequently a secondary vortex ring that follows the first.

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Composite Vertical Structure of Vertical Velocity in Nonprecipitating Cumulus Clouds

Monthly Weather Review ◽

10.1175/mwr-d-12-00047.1 ◽

2013 ◽

Vol 141 (5) ◽

pp. 1673-1692 ◽

Cited By ~ 6

Author(s):

Yonggang Wang ◽

Bart Geerts

Keyword(s):

Life Cycle ◽

Vortex Ring ◽

Vertical Velocity ◽

Circulation Pattern ◽

Liquid Water Content ◽

University Of Wyoming ◽

High Plains ◽

Cumulus Clouds ◽

The University ◽

Negatively Buoyant

Abstract Vertical transects of Doppler vertical velocity data, obtained from an airborne profiling millimeter-wave cloud radar, are composited for a large number of cumulus clouds (Cu) at various stages of their life cycle, to examine typical circulations patterns. The Cu clouds range in depth between ~500 and 6000 m and are generally nonprecipitating. They were sampled on board the University of Wyoming King Air over a mountain in southern Arizona during the summer monsoon, and over the high plains of southeastern Wyoming. The composite analysis shows clear evidence of an updraft/downdraft dipole in the upper cloud half, consistent with a horizontal vortex ring. A single cloud-scale toroidal circulation emerges notwithstanding the complex finescale structure with multiple vortices, commonly evident in individual transects of Cu clouds. The stratification of all Cu samples as a function of their buoyancy and mean vertical velocity shows that the vortex ring pattern tends to be more pronounced in positively buoyant Cu with rising motion (presumably young clouds) than in negatively buoyant and/or sinking Cu near the end of their life cycle. Yet no reverse vortex ring is observed in the latter Cu, suggesting that the decaying phase is short lived in these dry environments. The vortex-ring circulation pattern is more intense in the shallower Cu, which are also more buoyant and have a liquid water content closer to adiabatic values. Wind shear tends to tilt Cu clouds and their vortex ring, resulting in a broadening of the upshear updraft and downshear downdraft.

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Experimental observation elucidates vortex ring life cycle in non-Newtonian fluids

Scilight ◽

10.1063/1.5082956 ◽

2018 ◽

Vol 2018 (48) ◽

pp. 480007

Author(s):

Drew DeJarnette

Keyword(s):

Life Cycle ◽

Vortex Ring ◽

Experimental Observation ◽

Newtonian Fluids

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Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156791 ◽

1989 ◽

Vol 47 ◽

pp. 962-963

Author(s):

Betty Ruth Jones ◽

Steve Chi-Tang Pan

Keyword(s):

Nervous System ◽

Life Cycle ◽

Schistosoma Mansoni ◽

Snail Host ◽

Complex Life Cycle ◽

Rational Approach ◽

Effective Control ◽

The Social ◽

Social And Economic Development ◽

Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

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A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147570 ◽

1993 ◽

Vol 51 ◽

pp. 346-347

Author(s):

Randolph W. Taylor ◽

Henrie Treadwell

Keyword(s):

Plasma Membrane ◽

Life Cycle ◽

Growth Phase ◽

Filter Paper ◽

Physarum Polycephalum ◽

Freeze Fracture ◽

Petri Dish ◽

Wire Screen ◽

Wide Mouth ◽

Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

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