An improved flow evaluation scheme in orifices of different aspect ratios

Elmahdi, Abdelaziz M.; Newman, Brent E.; Perry, Gilbert J.; Costa, Fransisco; Agrawal, Dipak I.; Agrawal, Gopal; deCarvalho, Claudia T.; Nanda, Navin C.

doi:10.1016/s0301-5629(96)00228-1

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…The decrease of the acceleration coefficient with body size is more difficult to explain. It may be related to changes in the shape of the animal surrounding the inhalant aperture (Anayiotos et al 1995 ), or to changes in aspect-ratio (length/width) of the inhalant aperture (Anayiotos et al 1997 ). For a liquid with the same viscosity as blood, Anayiotos et al ( 1997 ) showed that a higher aspect-ratio in an oval shaped orifice resulted in a steeper velocity profile.…”

Section: Discussionmentioning

confidence: 99%

Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas, Mytilus edulis and Cerastoderma edule, in relation to food competition

et al. 2009

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Introduced Pacific oysters (Crassostrea gigas) have shown rapid expansion in the Oosterschelde estuary, while stocks of native bivalves declined slightly or remained stable. This indicates that they might have an advantage over native bivalve filter feeders. Hence, at the scale of individual bivalves, we studied whether this advantage occurs in optimizing food intake over native bivalves. We investigated feeding current characteristics, in which potential differences may ultimately lead to a differential food intake. We compared feeding currents of the invasive epibenthic non-siphonate Pacific oyster to those of two native bivalve suspension feeders: the epibenthic siphonate blue mussel Mytilus edulis and the endobenthic siphonate common cockle Cerastoderma edule. Inhalant flow fields were studied empirically using digital particle image velocimetry and particle tracking velocimetry. Exhalant jet speeds were modelled for a range of exhalant-aperture cross-sectional areas as determined in the laboratory and a range of filtration rates derived from literature. Significant differences were found in inhalant and exhalant current velocities and properties of the inhalant flow field (acceleration and distance of influence). At comparable body weight, inhalant current velocities were lower in C. gigas than in the other species. Modelled exhalant jets were higher in C. gigas, but oriented horizontally instead of vertically as in the other species. Despite these significant differences and apparent morphological differences between the three species, absolute differences in feeding current characteristics were small and are not expected to lead to significant differences in feeding efficiency.

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Section: Discussionmentioning

confidence: 99%

Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas, Mytilus edulis and Cerastoderma edule, in relation to food competition

et al. 2009

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“…Vandervoort et al 1,14 used multiple correlations to determine the location of the ori ce and to subsequently calculate the regurgitant ow. Anayiotos et al and Myers et al [26][27][28] have proposed a remarkable approach based on a precise description of the isovelocity surfaces and excluding any simpli cation in terms of velocity elds. Schwammenthal et al 13 validated a detailed analysis of the velocity pro le that allowed determination of the aliasing velocity, allowing an accurate evaluation of the regurgitant ow.…”

Section: Comparison With Similar Studiesmentioning

confidence: 99%

“…None of these studies simultaneously addressed the two sources of errors: the positioning of the ori ce and the selection of the velocity at which the radius is measured. Anayiotos et al and Myers et al [26][27][28] have proposed a remarkable approach based on a precise description of the isovelocity surfaces and excluding any simpli cation in terms of velocity elds. The hemiellipses were either directly imaged or calculated after several ttings of the observed centerline velocity pro les with theoretical data derived from numerical simulations including "a priori" informations.…”

Section: Comparison With Similar Studiesmentioning

confidence: 99%

In Vitro Validation of a New Approach for Quantitating Regurgitations Using Proximal Isovelocity Surface Area

et al. 2000

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The present work has been designed to validate the calculation of the effective regurgitant orifice (ERO) area with the use of a new formula that takes into account the velocity profile (V(r) vs r) and that is insensitive to errors in the determination of the position of the orifice. Assuming a hemispheric model, ERO = 2 pi r(2). V(r)/V(o) (with V(o) = velocity at the orifice) and (V(o)/V(r))(0.5) = (2 pi/ERO)(0.5) r. Thus, the slope of the corresponding linear regression allows ERO to be calculated as: ERO = 2 pi/slope(2). This approach was tested in vitro in pulsatile conditions on circular, conical, and slit-like orifices. The calculated ERO was compared with the actual jet cross sectional area derived from the transverse velocity profile at the jet origin. For the purpose of comparison, the "classical" ERO was calculated for all the configurations, angulations, and threshold velocities. The relationship between (V(o)/V(r))(0.5) was linear (r > 0.98) over a wide range of velocities. The nonhemispheric components were found to modify the constant and not the slope. The mean variation of the calculated ERO was 6.5%. The correlation between the calculated and the actual ERO was very close (>0.97) with slope equal to 0.96. By comparison with the new method, the classical formula gave an underestimation of the ERO that dramatically increased when studying the flow closer to the orifice or in the case of error on the measurement of r. In conclusion, a method using velocity profiles instead of isolated values improves the accuracy of the proximal isovelocity surface area (PISA) method for measuring the ERO.

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Evaluation of 3-D colour Doppler ultrasound for the measurement of proximal isovelocity surface area

deGroot

Drangova

Fenster

et al. 2000

Ultrasound in Medicine & Biology

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An improved flow evaluation scheme in orifices of different aspect ratios

Cited by 5 publications

References 14 publications

Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas, Mytilus edulis and Cerastoderma edule, in relation to food competition

Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas, Mytilus edulis and Cerastoderma edule, in relation to food competition

In Vitro Validation of a New Approach for Quantitating Regurgitations Using Proximal Isovelocity Surface Area

Evaluation of 3-D colour Doppler ultrasound for the measurement of proximal isovelocity surface area

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