Vortex Rings in Bio-Inspired and Biological Jet Propulsion

Krueger, Paul S.; Moslemi, Ali; Nichols, J. Tyler; Bartol, Ian K.; Stewart, William J.

doi:10.4028/3-908158-15-x.237

Cited by 10 publications

(13 citation statements)

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“…In jet mode II, which was associated with greater thrust but lower propulsive efficiency, part of the fluid was entrained into a leading vortex ring but the remainder formed a long trailing jet. The finding that isolated vortex rings were more efficient than vortex rings with trailing jets is consistent with studies using mechanical pulsed jets (Krueger et al 2008). Though Bartol et al (2009) used a different propulsive efficiency equation, my calculations show that P.…”

Section: Aspects Of Salp Jet Wake Structuresupporting

confidence: 79%

“…Based on an analytical model, Weihs (1977) showed that closelyspaced periodic jets result in substantial increases in thrust. More recent studies with squid and a mechanical pulsed-jet vehicle have confirmed a thrust benefit from pulsing compared to a continuous jet (Krueger et al 2008). As a vortex ring forms, ambient fluid is accelerated and entrained in the growing ring.…”

Section: Aspects Of Salp Jet Wake Structurementioning

confidence: 93%

“…Variation in siphon diameter can delay pinch off of the ring from a trailing jet so that even more fluid is entrained in the vortex ring . Each of these features, characteristic of salp jet propulsion, were associated with the entrainment of additional, ambient fluid which leads to increased thrust (Dabiri 2009, Krueger et al 2008). …”

Section: Aspects Of Salp Jet Wake Structurementioning

confidence: 99%

“…Both methods of flow visualization showed that in all species examined, forward swimming is accomplished by vortex ring propulsion. The jet can be described as a fully-pulsed jet, meaning there was a period of no flow separating pulses (Krueger et al 2008). Fluid inside the body of the salp was accelerated as circular muscle bands contract and is ejected via the atrial siphon.…”

Section: Structure Of Propulsive Jet Wakesmentioning

confidence: 99%

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Form, function and flow in the plankton : jet propulsion and filtration by pelagic tunicates

Sutherland¹

2010

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Trade-offs between filtration rate and swimming performance among several salp species with distinct morphologies and swimming styles were compared. Small-scale particle encounter at the salp filtering apparatus was also explored. Observations and experiments were conducted at the Liquid Jungle Lab, off the pacific coast of Panama in January 2006 through 2009. First, time-varying body volume was calculated by digitizing salp outlines from in situ video sequences. The resulting volume flow rates were higher than previous measurements, setting an upper limit on filtration capacity. Though each species possessed a unique combination of body kinematics, normalized filtration rates were comparable across species, with the exception of significantly higher rates in Weelia cylindrica aggregates, suggesting a tendency towards a flow optimum. Secondly, a combination of in situ dye visualization and particle image velocimetry (PIV) measurements were used to describe properties of the jet wake and swimming performance variables including thrust, drag and propulsive efficiency. All species investigated swam via vortex ring propulsion. Though Weelia cylindrica was the fastest swimmer, Pegea confoederata was the most efficient, producing the highest weight-specific thrust and wholecycle propulsive efficiency. Weak swimming performance parameters in Cyclosalpa affinis, including low weight-specific thrust and low propulsive efficiency, may be compensated by comparatively low energetic requirements. Finally, a low Reynolds number mathematical model using accurately measured parameters and realistic oceanic particle size concentrations showed that submicron particles are encountered at higher rates than larger particles. Results from feeding experiments with 0.5, 1 and 3 μm polystyrene microspheres corroborated model predictions. Though 1 to 10 μm-sized particles (e.g. flagellates, small diatoms) are predicted to provide four times as much carbon as 0.1 to 1 μm-sized particles (e.g. bacteria, Prochlorococcus), particles smaller than the mesh size (1.4 μm) can still fully satisfy salp energetic needs.

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Section: Aspects Of Salp Jet Wake Structuresupporting

confidence: 79%

Section: Aspects Of Salp Jet Wake Structurementioning

confidence: 93%

Section: Aspects Of Salp Jet Wake Structurementioning

confidence: 99%

Section: Structure Of Propulsive Jet Wakesmentioning

confidence: 99%

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Form, function and flow in the plankton : jet propulsion and filtration by pelagic tunicates

Sutherland¹

2010

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“…Technically, the CWJT deals with fluid momentum, as the consequence from fluid volume differentiation which involves the contraction and expanding process. Some would refer the reaction from the fluid momentum as impulse, where it obeys Newton I11 law [4], [5]. Unlike the continuous water jet thruster, this CWJT generates the jet periodically, to ensure the fluid is fully encapsulated for a maximum thrust during contraction [6].…”

Section: Introductionmentioning

confidence: 99%

2D Contractile Water Jet Thruster Characterization for Bio-Inspired Underwater Robot Locomotion

Shaari

Samad

2014

AMM

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Abstract.This research was conducted to analyze the thrust performance generated from a two dimensional contractile water jet thruster (CWJT). The main aim of this research is to investigate the relation and reaction between the input parameters of the contractile water jet thruster. The major parameter of this study is the actuating force as the input and the thrust force as the output. In addition to these parameters, nozzle area and fluid velocity influence were also considered in the investigation. Two pneumatic cylinders were applied to actuate the contraction. Thrust force was measured by both experimentally and theoretically. Generally the increment of the contraction force increases the thmst force. However, generated thrust at different contraction force depends on the size of the nozzle.

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