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Unsteady laminar boundary layers of rainbow trout swimming in turbulent flows

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Unsteady laminar boundary layers of rainbow trout swimming in turbulent flows. / Yanase, Kazutaka; Saarenrinne, Pentti.

In: Biology Open, 08.11.2016.

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Yanase, Kazutaka ; Saarenrinne, Pentti. / Unsteady laminar boundary layers of rainbow trout swimming in turbulent flows. In: Biology Open. 2016.

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@article{eccd40b0114f43cc85b015275aa546c3,
title = "Unsteady laminar boundary layers of rainbow trout swimming in turbulent flows",
abstract = "The boundary layers of rainbow trout, Oncorhynchus mykiss [mean±s.d., 0.231±0.016 m total-body-length (L); N=6], swimming at 1.6±0.09 L s(-1) (N=6) in an experimental flow channel (the Reynolds number, Re=4×10(5)) with medium turbulence (5.6{\%}-intensity) were examined using the particle image velocimetry technique. The tangential-flow-velocity distributions in the pectoral (arc-length from the rostrum, lx=71±8 mm, N=3) and pelvic surface regions (lx=110±13 mm, N=4) were approximated by a laminar-boundary-layer model, the Falkner-and-Skan equation. The flow regime over the pectoral and pelvic surfaces was regarded as a laminar flow, which could create less skin-friction drag than would be the case with turbulent flow. Flow separation was postponed until vortex shedding occurred over the posterior surface (lx=163±22 mm, N=3). The ratio of the body-wave velocity to the swimming speed was in the order of 1.2. This was consistent with the condition of the boundary-layer laminarisation that had been confirmed earlier using a mechanical model. These findings suggest an energy-efficient swimming strategy for rainbow trout in a turbulent environment.",
author = "Kazutaka Yanase and Pentti Saarenrinne",
note = "{\circledC} 2016. Published by The Company of Biologists Ltd.",
year = "2016",
month = "11",
day = "8",
doi = "10.1242/bio.020008",
language = "English",
journal = "Biology Open",
issn = "2046-6390",
publisher = "Company of Biologists",

}

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TY - JOUR

T1 - Unsteady laminar boundary layers of rainbow trout swimming in turbulent flows

AU - Yanase, Kazutaka

AU - Saarenrinne, Pentti

N1 - © 2016. Published by The Company of Biologists Ltd.

PY - 2016/11/8

Y1 - 2016/11/8

N2 - The boundary layers of rainbow trout, Oncorhynchus mykiss [mean±s.d., 0.231±0.016 m total-body-length (L); N=6], swimming at 1.6±0.09 L s(-1) (N=6) in an experimental flow channel (the Reynolds number, Re=4×10(5)) with medium turbulence (5.6%-intensity) were examined using the particle image velocimetry technique. The tangential-flow-velocity distributions in the pectoral (arc-length from the rostrum, lx=71±8 mm, N=3) and pelvic surface regions (lx=110±13 mm, N=4) were approximated by a laminar-boundary-layer model, the Falkner-and-Skan equation. The flow regime over the pectoral and pelvic surfaces was regarded as a laminar flow, which could create less skin-friction drag than would be the case with turbulent flow. Flow separation was postponed until vortex shedding occurred over the posterior surface (lx=163±22 mm, N=3). The ratio of the body-wave velocity to the swimming speed was in the order of 1.2. This was consistent with the condition of the boundary-layer laminarisation that had been confirmed earlier using a mechanical model. These findings suggest an energy-efficient swimming strategy for rainbow trout in a turbulent environment.

AB - The boundary layers of rainbow trout, Oncorhynchus mykiss [mean±s.d., 0.231±0.016 m total-body-length (L); N=6], swimming at 1.6±0.09 L s(-1) (N=6) in an experimental flow channel (the Reynolds number, Re=4×10(5)) with medium turbulence (5.6%-intensity) were examined using the particle image velocimetry technique. The tangential-flow-velocity distributions in the pectoral (arc-length from the rostrum, lx=71±8 mm, N=3) and pelvic surface regions (lx=110±13 mm, N=4) were approximated by a laminar-boundary-layer model, the Falkner-and-Skan equation. The flow regime over the pectoral and pelvic surfaces was regarded as a laminar flow, which could create less skin-friction drag than would be the case with turbulent flow. Flow separation was postponed until vortex shedding occurred over the posterior surface (lx=163±22 mm, N=3). The ratio of the body-wave velocity to the swimming speed was in the order of 1.2. This was consistent with the condition of the boundary-layer laminarisation that had been confirmed earlier using a mechanical model. These findings suggest an energy-efficient swimming strategy for rainbow trout in a turbulent environment.

U2 - 10.1242/bio.020008

DO - 10.1242/bio.020008

M3 - Article

JO - Biology Open

JF - Biology Open

SN - 2046-6390

ER -