Patterns for efficient propulsion during the energy evolution of vortex rings

Xiang, Yang; Qin, Suyang; Liu, Hong

doi:10.1016/j.euromechflu.2018.03.014

Cited by 13 publications

(6 citation statements)

References 49 publications

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“…Emerging techniques to observe and measure fluid dynamics in live-animal experiments and simulations are transforming biomechanical concepts of swimming efficiency in cephalopods. New work presents greater attention to pressure zones (Dabiri et al 2014; Gemmell et al 2015), wakes and eddies (Peng and Dabiri 2008), and spiral vortices (Bartol et al 2016; Neil and Askew 2018; Xiang et al 2018). Cephalopod jet propulsion, long regarded as woefully inefficient (e.g., Wells 1990; O'Dor 2002), is now shown to induce vortex fields that increase efficiency at increasing velocity for both squid ( Lolliguncula brevis ; Bartol et al 2016) and Nautilus (Neil and Askew 2018).…”

Section: Discussionmentioning

confidence: 99%

Hydrodynamic trade-offs in potential swimming efficiency of planispiral ammonoids

Ritterbush¹,

Hebdon²

2023

Paleobiology

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Ammonoid cephalopods were Earth's most abundant oceanic carnivores for hundreds of millions of years, yet their probable range of swimming capabilities is poorly constrained. We investigate potential hydrodynamic costs and advantages provided by different conch geometries using computational fluid dynamics simulations. Simulations of raw drag demonstrate expected increases with velocity and conch inflation, consistent with published experimental data. Analysis at different scales of water turbulence (via Reynolds number) reveals dynamic trade-offs between conch shape, size, and velocity. Among compressed shells, the cost of umbilical exposure makes little difference at small sizes (and/or low velocity) but is profound at large sizes (and/or high velocity). We estimate that small ammonoids could travel one to three diameters per second (i.e., a typical ammonoid with a 5-cm-diameter shell could travel 5–15 cm/s), but that large ammonoids faced greater discrepancies (a 10 cm serpenticone likely traveled <30 cm/s, while a 10 cm oxycone might achieve >40 cm/s). All of these velocities are proposed only for short bursts of jet propulsion, lasting only a few seconds, in the service of dodging a predator or conspecific rival. These analyses do not include phylogeny, taxonomy, second-order conch architecture (ribs, ornament, etc.), or hydrostatic consequences of internal anatomy (soft body, suture complexity). For specific paleoecological context, we consider how these results inform our reconstruction of Jurassic ammonite recovery from the end-Triassic mass extinction. Greater refinements will come with additional simulations that measure how added mass is influenced by individual shape-trait variations, ornament, and subtle body extensions during a single jet motion.

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Section: Discussionmentioning

confidence: 99%

Hydrodynamic trade-offs in potential swimming efficiency of planispiral ammonoids

Ritterbush¹,

Hebdon²

2023

Paleobiology

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“…However, our results have analytically substantiated the impact of oblique cut of the active-flow nozzle to form an operating vortex flow. Moreover, patterns for efficient propulsion during the energy evolution of vortex rings is presented in [37].…”

Section: Discussionmentioning

confidence: 99%

Flow Modeling in a Vortex Chamber of a Liquid–Steam Jet Apparatus

et al. 2022

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The article investigated the flow of boiling streams through a nozzle with an oblique cut. Due to this flow organization, deviation from the nozzle axis at the vortex chamber inlet occurred. The study of flow modeling in the inlet section was carried out. The flow design and the calculation scheme of the vortex liquid–steam jet apparatus were proposed. Analytical expressions between the main operating parameters were obtained according to the developed mathematical model. A recommended oblique-cut angle for the active-flow nozzle was evaluated considering the transition through the first critical section based on the tangential velocity flow model. Validation of the mathematical model in the inlet section of the vortex chamber was provided based on the comparison with available experimental data. Flow visualization in the inlet section of the vortex chamber was obtained. The assumption of uneven flow distribution was confirmed experimentally. Overall, the boiling liquid flow was implemented in the active flow nozzle. The obtained scientific and practical results help to determine geometric parameters and physical characteristics of the vortex-type liquid–steam jet apparatus at the design stage. The obtained results were implemented to modernize vacuum units based on vortex type liquid–steam jet apparatuses.

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“…The pinch‐off mechanism of the vortex ring makes it impossible to grow indefinitely. In follow‐up studies, 14–19 it was found that the formation of the vortex ring was also related to the non‐pulse velocity program. When the piston is started in different velocity programs, there are obvious differences in the velocity distribution at the open interface of the generator, affecting the environmental circulation and the evolution of the vortex ring, which further affects the formation number of the vortex ring.…”

Section: Introductionmentioning

confidence: 99%

“…The pinchoff mechanism of the vortex ring makes it impossible to grow indefinitely. In follow-up studies, [14][15][16][17][18][19] it was found that the formation of the vortex ring was also related to the non-pulse velocity program.…”

Section: Introductionmentioning

confidence: 99%

Flow characteristics and formation optimization of vortex ring air supply

et al. 2022

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The vortex rings ventilation (VRV) is a new type of air supply system comprising vortex rings. Compared with an air supply jet, a vortex ring reduces the loss of fresh air during transportation because of its stable structure. However, during the formation of the vortex ring, it entrains the ambient air and reduces the fresh air in the vortex ring. In this study, a vortex ring generator with a fresh air cavity is proposed to form confined vortex rings. This improved the fresh air ratio of the VRV. Based on previous experiments, a piston‐orifice axisymmetric model with a dynamic grid was developed to form an air vortex ring. The flow characteristics of free and confined vortex rings during the generation stage were studied. First, the evolution of free vortex rings with different stroke lengths was studied, and the optimal piston stroke length and radial constraint size were determined. Subsequently, the mixing ratios of the free and confined vortex rings were compared and analyzed. The results showed that the mixing ratio of the confined vortex ring formed by the fresh air cavity in the formation stage was zero. Moving to the location of 4.9 times the orifice diameter (D0$$ {D}_0 $$), reduced the mixing ratio of the confined vortex ring by 77.78% compared with that of the free vortex ring. In addition, the influence of three inner diameters and four outlet diameters of fresh air cavities on the vortex rings was studied to optimize the size of the vortex ring generator. The results showed that the inner diameter of the fresh air cavity was greater than 3D0$$ 3{D}_0 $$ and that an outlet diameter greater than 2.5D0$$ 2.5{D}_0 $$ had little influence on the vortex rings.

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Patterns for efficient propulsion during the energy evolution of vortex rings

Cited by 13 publications

References 49 publications

Hydrodynamic trade-offs in potential swimming efficiency of planispiral ammonoids

Hydrodynamic trade-offs in potential swimming efficiency of planispiral ammonoids

Flow Modeling in a Vortex Chamber of a Liquid–Steam Jet Apparatus

Flow characteristics and formation optimization of vortex ring air supply

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