<i>Life in Moving Fluids</i>

Vogel, Steven; Gollub, Jerry P.

doi:10.1063/1.2807982

Cited by 243 publications

(332 citation statements)

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“…A streamlined shape is characterized by a blunt, rounded leading edge, maximum thickness located one third to one half of the chord posterior of the leading edge, and tapering toward the trailing edge. The rounded leading edge, position of the shoulder, and sharp trailing edge is crucial for lift generation, while minimizing drag (Webb, 1975;Vogel, 1994).…”

Section: Discussionmentioning

confidence: 99%

“…The favorable and adverse pressure gradients are located upstream and downstream of SP, respectively. The adverse pressure gradient facilitates flow separation from the fluke surface and results in a large increase in drag (Webb, 1975;Vogel, 1994). By displacement of SP further downstream on the fluke section, separation can be delayed by promoting a longer favorable pressure gradient.…”

Section: Discussionmentioning

confidence: 99%

“…By displacement of SP further downstream on the fluke section, separation can be delayed by promoting a longer favorable pressure gradient. Engineered ''laminar'' foils have a far posteriorly displaced SP (0.45) to delay separation and reduce drag (Vogel, 1981;Pavlov, 2003). Researchers believe that more posterior SP is associated with faster swimming whales (Shpet, 1975).…”

Section: Discussionmentioning

confidence: 99%

“…Structurally, the flukes are composed of fibrous connective tissue (Felts, 1966). Biomechanically, the flukes act like a pair of wings (Vogel, 1994). Thrust is generated as a component of an anteriorly directed lift force as the flukes are vertically oscillated (Fish, 1998a,b).…”

mentioning

confidence: 99%

“…Cross-sectional profiles of the flukes along the longitudinal axis display a conventional streamlined foil profile with a rounded leading edge and long tapering trailing edge. This shape is crucial for generation of lift for thrust, while minimizing drag (Lighthill, 1970;Vogel, 1994). The flukes are symmetrical about the chord (Lang, 1966;Bose et al, 1990).…”

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confidence: 99%

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Examination of the three‐dimensional geometry of cetacean flukes using computed tomography scans: Hydrodynamic implications

Fish

Beneski

Ketten

2007

The Anatomical Record

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The flukes of cetaceans function in the hydrodynamic generation of forces for thrust, stability, and maneuverability. The three-dimensional geometry of flukes is associated with production of lift and drag. Data on fluke geometry were collected from 19 cetacean specimens representing eight odontocete genera (Delphinus, Globicephala, Grampus, Kogia, Lagenorhynchus, Phocoena, Stenella, Tursiops). Flukes were imaged as 1 mm thickness cross-sections using X-ray computer-assisted tomography. Fluke shapes were characterized quantitatively by dimensions of the chord, maximum thickness, and position of maximum thickness from the leading edge. Sections were symmetrical about the chordline and had a rounded leading edge and highly tapered trailing edge. The thickness ratio (maximum thickness/chord) among species increased from insertion on the tailstock to a maximum at 20% of span and then decreasing steadily to the tip. Thickness ratio ranged from 0.139 to 0.232. These low values indicate reduced drag while moving at high speed. The position of maximum thickness from the leading edge remained constant over the fluke span at an average for all species of 0.285 chord. The displacement of the maximum thickness reduces the tendency of the flow to separate from the fluke surface, potentially affecting stall patterns. Similarly, the relatively large leading edge radius allows greater lift generation and delays stall. Computational analysis of fluke profiles at 50% of span showed that flukes were generally comparable or better for lift generation than engineered foils. Tursiops had the highest lift coefficients, which were superior to engineered foils by 12-19%. Variation in the structure of cetacean flukes reflects different hydrodynamic characteristics that could influence swimming performance. Anat Rec, 290:614-623, 2007Rec, 290:614-623, . 2007 Wiley-Liss, Inc.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Examination of the three‐dimensional geometry of cetacean flukes using computed tomography scans: Hydrodynamic implications

Fish

Beneski

Ketten

2007

The Anatomical Record

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Larval antennal sensilla in water-living insects

Gaino

Rebora

1999

Microsc. Res. Tech.

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An overview of larval antennal sensilla in hemimetabolous and holometabolous water-living insects is given by updating current knowledge on the fine structure of these sensory systems. In the absence of successful electrophysiological studies, the possible function of sensilla is deduced from their architecture. Various kinds of sensilla are described in hemimetabolous insects, such as Ephemeroptera, Odonata, and Plecoptera, and holometabolous insects, such as Diptera Nematocera (Culicidae, Simuliidae, Psychodidae, Chaoboridae) and Trichoptera. Their possible function in responding to stimuli from the freshwater environment is illustrated and discussed. The importance of sensilla as taxonomic and phylogenetic traits is reported in Baetidae (Ephemeroptera) and in Diptera Nematocera. Some homologies outlined in Diptera Nematocera give evidence of a link between species, such as Chaoboridae and Psychodidae, whose antennae are highly modified, prehensile in the former and very reduced in the latter. Particular features, such as cuticle without pores in chemosensory sensilla and naked perikarya, are so far found exclusively in some water-living arthropods, thus reflecting a possible adaptation to the aquatic habitat. The structure of sensilla and chloride cells, which have a similar external morphology, is presented and discussed in various insect groups, considering the possible derivation of the chloride cells from sensilla.

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Oscillation characteristics of biofilm streamers in turbulent flowing water as related to drag and pressure drop

Stoodley

Lewandowski

Boyle

et al. 1998

Biotechnol. Bioeng.

123

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Mixed population biofilms consisting of Pseudomonas aeruginosa, P. fluorescens, and Klebsiella pneumoniae were grown in a flow cell under turbulent conditions with a water flow velocity of 18 cm/s (Reynolds number, Re, =1192). After 7 days the biofilms were patchy and consisted of cell clusters and streamers (filamentous structures attached to the downstream edge of the clusters) separated by interstitial channels. The cell clusters ranged in size from 25 to 750 μm in diameter. The largest clusters were approximately 85 μm thick. The streamers, which were up to 3 mm long, oscillated laterally in the flow. The motion of the streamers was recorded at various flow velocities up to 50.5 cm/s (Re 3351) using confocal scanning laser microscopy. The resulting time traces were evaluated by image analysis and fast Fourier transform analysis (FFT). The amplitude of the motion increased with flow velocity in a sigmoidal shaped curve, reaching a plateau at an average fluid flow velocity of approximately 25 cm/s (Re 1656). The motion of the streamers was possibly limited by the flexibility of the biofilm material. FFT indicated that the frequency of oscillation was directly proportional to the average flow velocity (u(ave)) below 9.5 cm/s (Re 629). At u(ave) greater than 9.5 cm/s, oscillation frequencies were above our measurable frequency range (0.12–6.7 Hz). The oscillation frequency was related to the flow velocity by the Strouhal relationship, suggesting that the oscillations were possibly caused by vortex shedding from the upstream biofilm clusters. A loss coefficient (k) was used to assess the influence of biofilm accumulation on pressure drop. The k across the flow cell colonized with biofilm was 2.2 times greater than the k across a clean flow cell. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 536‐544, 1998.

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Life in Moving Fluids

Cited by 243 publications

References 0 publications

Examination of the three‐dimensional geometry of cetacean flukes using computed tomography scans: Hydrodynamic implications

Examination of the three‐dimensional geometry of cetacean flukes using computed tomography scans: Hydrodynamic implications

Larval antennal sensilla in water-living insects

Oscillation characteristics of biofilm streamers in turbulent flowing water as related to drag and pressure drop

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