Bidirectional cyclical flows increase energetic costs of station holding for a labriform swimming fish, Cymatogaster aggregata

Abstract Wave-induced surge conditions are found in shallow marine ecosystems worldwide; yet, few studies have quantified how cyclical surges may affect free swimming animals. Here, we used a recently adapted respirometry technique to compare the energetic costs of a temperate fish species (Cymatogaster aggregata) swimming against a steady flow versus cyclical unidirectional and bidirectional surges in which unsteady swimming (such as accelerating, decelerating and turning) occurs. Using oxygen uptake (ṀO2) as an estimate of energetic costs, our results reveal that fish swimming in an unsteady (i.e. cyclical) unidirectional flow showed no clear increase in costs when compared to a steady flow of the same average speed, suggesting that costs and savings from cyclical acceleration and coasting are near equal. Conversely, swimming in a bidirectional cyclical flow incurred significantly higher energetic costs relative to a steady, constant flow, likely due to the added cost of turning around to face the changing flow direction. On average, we observed a 50% increase in ṀO2 of fish station holding within the bidirectional flow (227.8 mg O2 kg−1 h−1) compared to a steady, constant flow (136.1 mg O2 kg−1 h−1) of the same mean velocity. Given wave-driven surge zones are prime fish habitats in the wild, we suggest the additional costs fish incur by station holding in a bidirectional cyclical flow must be offset by favourable conditions for foraging and reproduction. With current and future increases in abiotic stressors associated with climate change, we highlight the importance of incorporating additional costs associated with swimming in cyclical water flow in the construction of energy budgets for species living in dynamic, coastal habitats.

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Abstract 249: Stationary Signal and Flow Velocity Assessment by MRI of a New Nitinol Nanocomposite Polymer Stent-Graft

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.32.suppl_1.a249 ◽

2012 ◽

Vol 32 (suppl_1) ◽

Author(s):

Mital Desai ◽

Rachel E Clough ◽

Nicholas R Gaddum ◽

Kawal Rhode ◽

Xiang Zhou ◽

...

Keyword(s):

Steady Flow ◽

Stent Graft ◽

Signal Attenuation ◽

Stent Grafts ◽

Mean Velocity ◽

Nanocomposite Polymer ◽

Significant Difference ◽

Flow Phantom ◽

Flow Flux ◽

Commercial Device

Objective: To assess MRI compatibility and suitability of a new sutureless stent-graft made from Nitinol bonded to nanocomposite polymer (NP). Methods: 1. Using MRI and Magnevist contrast, isotropic 3D T1-weighted FFE images of NP stent-graft were acquired to observe artefacts and stationary signal attenuation. Average signal magnitude was calculated. Medtronic ValiantTM was used as control. 2. In second stage, steady flow phantom was setup for flow-encoded MRI signal assessment of both stent-grafts. Baseline values were obtained by velocity measurements without stent-graft using identical settings. 2D through-plane phase contrast images were acquired and average velocity and amount of flow (flux) were calculated. Results: On static assessment of NP and ValiantTM stent-grafts no significant image artefacts were seen. The signal inside and outside the ValiantTM stent-graft was 644.2(SD 36.2) and 659.6(SD 85.8) respectively. The signal attenuation for this device was 2.39%. The signal inside and outside the NP stent graft was 1561.7(SD 31.2) and 1595.5(SD 40.8) respectively with comparable signal attenuation of 2.16%. In MRI velocity attenuation study, steady flow phantom was set at mean volume of 105.3 ml and mean velocity of 79.5 cm/sec. Flux measured in ValiantTM stent-graft was 102±2.27 ml/sec with no significant difference to baseline (104±1.98 ml/sec; P=0.892). Similarly flux for NP stent-graft at mean stroke volume 104.4 ml and mean velocity of 92.3 cm/sec showed no difference to baseline (99.8±2.4 vs. 104±0.96 ml/sec; P=0.176). There was no significant difference in flux between Medtronic and NP stent-grafts (102±2.27 vs. 99.8±2.4 ml/sec; P=0.328). Conclusion: NP stent-graft does not display any material-induced artefacts on MRI. On flow assessment, signal attenuation is comparable with the commercial device. These properties are important in developing this stent-graft, compliant, durable, visco-elastic, biocompatible and anti-thrombogenic, for future clinical use.

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Improvement of Surface Morphology by Solution Flow Control in Solution Growth of SiC on Off-Axis Seeds

Materials Science Forum ◽

10.4028/www.scientific.net/msf.821-823.31 ◽

2015 ◽

Vol 821-823 ◽

pp. 31-34 ◽

Cited By ~ 5

Author(s):

Tomonori Umezaki ◽

Daiki Koike ◽

S. Harada ◽

Toru Ujihara

Keyword(s):

Flow Direction ◽

Seed Crystal ◽

Solution Growth ◽

Rotational Axis ◽

Solution Flow ◽

Step Flow ◽

Unidirectional Flow ◽

Novel Method ◽

Set Up ◽

Freshwater Mussel Bed Habitat in an Alluvial Sand-Bed-Material-Dominated Large River: A Core Flow Sediment Refugium?

Diversity ◽

10.3390/d12050174 ◽

2020 ◽

Vol 12 (5) ◽

pp. 174

Author(s):

Alan D. Christian ◽

Andrew J. Peck ◽

Ryan Allen ◽

Raven Lawson ◽

Waylon Edwards ◽

...

Keyword(s):

Flow Direction ◽

Freshwater Mussel ◽

Physical Habitat ◽

Stream Power ◽

Mussel Bed ◽

Mean Velocity ◽

Core Flow ◽

White River ◽

Bed Material ◽

Mussel Habitat

Habitat degradation, organismal needs, and other effects influencing freshwater mussel declines have been subject to intense focus by conservationists for the last thirty plus years. While researchers have studied the physical habitat requirements and needs of mussels in small- to medium-sized rivers with variable levels of success, less research has been conducted on mussel habitat in larger non-wadeable rivers, especially at the reach scale, where core flow environmental conditions provide and maintain habitat for freshwater mussels. We designed a quasi-experimental observational field study to examine seven hydrologic energy and material variables laterally and longitudinally at Current and Extirpated mussel bed habitat reaches in lower White River, Arkansas, a large non-wadeable, sand-bed-material-dominated river. As expected, lateral and longitudinal hydrologic variable differences were identified within a reach. Mean velocity, bed velocity, the Froude number, and stream power were all significantly lower at Current mussel bed habitat stations within a sampling reach. Energy regime differences in shear stress and, marginally, stream power were higher at Extirpated mussel bed habitat reaches. Several factors emerged as important to mussel habitat in the White River. First, bed velocity warrants further exploration in terms of both flow strength and flow direction. Second, bedload appears to be the primary contributor to mussel habitat but requires additional exploration within the context of core and secondary flow pathway interactions. The combined empirical evidence from our study supports the flow refugium concept identified for mussel habitats in smaller systems but expands the concept to large non-wadeable streams and includes reach-scale refuge from sediment transport conditions.

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Energetics: the costs of living and reproducing for an individual cephalopod

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1996.0095 ◽

1996 ◽

Vol 351 (1343) ◽

pp. 1083-1104 ◽

Cited By ~ 46

Keyword(s):

Specific Dynamic Action ◽

Energy Budgets ◽

Food Conversion ◽

Laboratory Studies ◽

Feeding Rates ◽

Historical Factors ◽

In The Wild ◽

Excretion Rates ◽

The Cost ◽

Conversion Efficiencies

Cephalopods, like all other animals, have to decide how to allocate resources; maintenance processes, growth of somatic and reproductive tissues, and locomotor activity all have costs. We should like to be able to identify these costs and discover how efficiently cephalopods make use of the prey that they capture and digest. Cephalopods generally grow fast and mature rapidly; a first task is to determine how accurately laboratory studies reflect growth in the wild, because much of the information we need (such as food conversion efficiencies, excretion rates or the costs of locomotion) can be collected only from animals kept in the laboratory. Comparison of laboratory feeding and growth rates for octopods, sepioids and teuthoids with fisheries data suggests that data collected from cephalopods fed ad libitum in the laboratory may be used validly to construct energy budgets representative of individuals in the wild. The immediate cost of feeding (the specific dynamic action) has been thoroughly documented in Octopus , as has the longer-term elevation or depression of metabolic rate by feeding or starvation; it is assumed that similar costs will be found in squid. The cost of locomotion has been studied in both octopods and squid, but we have only limited data on how much time the animals spend moving, and how rapidly, in the wild. Excretory and faecal losses are assessed from laboratory studies, and maintenance costs estimated from feeding rates that just maintain body mass in the laboratory. Comparison of gross and net food conversion efficiencies suggest that squid convert food into tissues less efficiently than octopods, owing primarily to their greater time spent in locomotion. We present a representative series of energy budgets for octopods (based on Octopus ) and squids (based on Illex and Loligo ), for starving, feeding, migrating and maturing individuals. A major contrast is provided by Nautilus, which lives for ten or twenty years and grows only slowly. Finally we speculate on the possible biochemical and historical factors that may have limited the adaptive radiation of cephalopods, resulting in a group lacking herbivores, detritivores or filter-feeders but extremely successful as carnivores.

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Measurements with a pulsed-wire and a hot-wire anemometer in the highly turbulent wake of a normal flat plate

Journal of Fluid Mechanics ◽

10.1017/s0022112076002218 ◽

1976 ◽

Vol 77 (3) ◽

pp. 473-497 ◽

Cited By ~ 71

Author(s):

L. J. S. Bradbury

Keyword(s):

Turbulent Flow ◽

Flat Plate ◽

Flow Direction ◽

Operating Conditions ◽

Turbulent Intensity ◽

Hot Wire ◽

Mean Flow ◽

Mean Velocity ◽

The Mean ◽

Better Than

This paper describes an investigation into the response of both the pulsed-wire anemometer and the hot-wire anemometer in a highly turbulent flow. The first part of the paper is concerned with a theoretical study of some aspects of the response of these instruments in a highly turbulent flow. It is shown that, under normal operating conditions, the pulsed-wire anemometer should give mean velocity and longitudinal turbulent intensity estimates to an accuracy of better than 10% without any restriction on turbulence level. However, to attain this accuracy in measurements of turbulent intensities normal to the mean flow direction, there is a lower limit on the turbulent intensity of about 50%. An analysis is then carried out of the behaviour of the hot-wire anemometer in a highly turbulent flow. It is found that the large errors that are known to develop are very sensitive to the precise structure of the turbulence, so that even qualitative use of hot-wire data in such flows is not feasible. Some brief comments on the possibility of improving the accuracy of the hot-wire anemometer are then given.The second half of the paper describes some comparative measurements in the highly turbulent flow immediately downstream of a normal flat plate. It is shown that, although it is not possible to interpret the hot-wire results on their own, it is possible to calculate the hot-wire response with a surprising degree of accuracy using the results from the pulsed-wire anemometer. This provides a rather indirect but none the less welcome check on the accuracy of the pulsed-wire results, which, in this very highly turbulent flow, have a certain interest in their own right.

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Imaging of Single Phase Flow in Porous Media by High Resolution MRI

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.113-116.126 ◽

2010 ◽

Vol 113-116 ◽

pp. 126-131 ◽

Cited By ~ 2

Author(s):

Lan Lan Jiang ◽

Yong Chen Song ◽

Yu Liu ◽

Yue Chao Zhao ◽

Ning Jun Zhu ◽

...

Keyword(s):

Porous Media ◽

High Resolution ◽

Velocity Distribution ◽

Flow Direction ◽

Spin Echo ◽

Flow Distribution ◽

Flow In Porous Media ◽

Mean Velocity ◽

High Resolution Mri ◽

Spin Echo Sequence

This paper presents the single flow in porous media to investigate CO2 flow velocity in porous media.We used high resolution MRI to visualize the fluid flow distribution and measure axial mean velocity in porous media.In the experiment, the porous media sample was packed with glass beads, with a porosity of around 0.4. Based the traditional spin echo sequence, we modified the sequence with flow encoding gradients in the flow direction .The sample was saturated. The water flow rates were 1ml/min、2ml/min、3ml/min and 5ml/min,respectively. First, the sequence was calibrated by pipe flow without porous media. As expected, the experimental images show parabolic velocity distribution. The velocity in the centre is high. Then the sample was measured with the same sequence. The images show that the velocity distribution is homogeneous in the porous media. In the boundary of the sample, the velocities are low because of wall-effect. Moreover, the mean velocities calculated from MRI images agree with the real velocities.These errors between calculated velocities and real velocities are small. It may be reduced by changing the experiment conditions.MRI is a useful technology for measuring flow in porous media.

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Sinusoidal Excitation of a Free Turbulent Jet With Constant Amplitude Transverse Pressure Gradients Near the Nozzle Exit: Part I: Measurement of Mean Shear Velocities

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.3426674 ◽

1973 ◽

Vol 95 (2) ◽

pp. 167-173

Author(s):

A. K. Stiffler ◽

J. L. Shearer

Keyword(s):

Nozzle Exit ◽

Flow Direction ◽

Excitation Frequency ◽

Velocity Profiles ◽

Turbulent Jet ◽

Pressure Gradients ◽

Mean Velocity ◽

Effective Velocity ◽

Gaussian Distribution Function ◽

The Mean

A free turbulent jet is perturbed transverse to the flow direction by a sinusoidal pressure gradient near the nozzle exit. Velocities in the jet are determined by hot wire anemometer measurements. Moving effective mean velocity profiles are defined and reconstructed from the point-by-point stationary measurements of the mean velocity and of the harmonic content of the time varying signal. The effective velocity profiles are described by the Gaussian distribution function where the spread parameter decays as the cube of the product of the excitation frequency and the downstream location from the nozzle. These profile measurements and analysis of their characteristics lead to a better understanding of the factors determining the gain of a fluidic amplifier under conditions of high frequency operation.

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Secondary Flow in Smooth and Rough Turbulent Circular Pipes: Turbulence Kinetic Energy Budgets

Fluids ◽

10.3390/fluids6120448 ◽

2021 ◽

Vol 6 (12) ◽

pp. 448

Author(s):

Paolo Orlandi ◽

Sergio Pirozzoli

Keyword(s):

Kinetic Energy ◽

Flow Direction ◽

Turbulence Kinetic Energy ◽

Energy Budgets ◽

Immersed Boundary ◽

Wall Region ◽

Turbulent Structures ◽

Circular Pipes ◽

Turbulence Kinetic Energy Budget ◽

Near Wall

Direct Numerical Simulations have been performed for turbulent flow in circular pipes with smooth and corrugated walls. The numerical method, based on second-order finite discretization together with the immersed boundary technique, was validated and applied to various types of flows. The analysis is focused on the turbulence kinetic energy and its budget. Large differences have been found in the near-wall region at low Reynolds number. The change in the near-wall turbulent structures is responsible for increase of drag and turbulence kinetic energy. To investigatselinae the effects of wall corrugations, the velocity fields have been decomposed so as to isolate coherent and incoherent motions. For corrugated walls, we find that coherent motions are strongest for walls covered with square bars aligned with the flow direction. In particular, the coherent contribution is substantial when the bars are spaced apart by a distance larger than their height. Detailed analysis of the turbulence kinetic energy budget shows for this set-up a very different behavior than for the other types of corrugations.

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Effect of Freestream Turbulence and Flow Recovery in the Wake of a Flat Plate

Volume 2: Symposia and General Papers, Parts A and B ◽

10.1115/fedsm2002-31166 ◽

2002 ◽

Author(s):

F. N. Krampa-Morlu ◽

R. Balachandar

Keyword(s):

Flat Plate ◽

Turbulence Intensity ◽

Flow Direction ◽

Wake Region ◽

Freestream Turbulence ◽

Near Wake ◽

Mean Velocity ◽

Channel Boundary ◽

The Mean ◽

Velocity Turbulence

The study of the recovery of an open channel boundary flow in the presence of increased freestream turbulence (FST) generated in the wake region of a surface mounted flat plate is presented. Detailed LDA velocity measurements were obtained upstream and downstream of the flat plate, which is 3 mm in thickness and has a thickness-to-chord ratio of 0.12. The chord is placed parallel to the flow direction. The characteristics of the mean velocity, turbulence intensity, and the velocity skewness and flatness factors were investigated. The skin friction was increased while the strength of the boundary layer wake parameter decreased in the wake region. The turbulence intensity profiles in the wake region increasingly deviated significantly from the upstream profile. Generally, the increased FST noticed in the near-wake region was observed to decay with downstream distance. As a result, the mean velocity and turbulence intensity profiles showed a general sense of recovery towards the state of the approaching flow.

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An Experimental Study of Heat Transfer of a Porous Channel Subjected to Oscillating Flow

Journal of Heat Transfer ◽

10.1115/1.1336510 ◽

2000 ◽

Vol 123 (1) ◽

pp. 162-170 ◽

Cited By ~ 62

Author(s):

H. L. Fu ◽

K. C. Leong ◽

X. Y. Huang ◽

C. Y. Liu

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Surface Temperature ◽

Steady Flow ◽

High Speed ◽

Flow Direction ◽

Porous Channel ◽

Oscillating Flow ◽

Oscillating Flows ◽

Nusselt Numbers

Experiments have been conducted to study the heat transfer of a porous channel subjected to oscillating flow. The surface temperature distributions for both steady and oscillating flows were measured. The local and length-averaged Nusselt numbers were analyzed. The experimental results revealed that the surface temperature distribution for oscillating flow is more uniform than that for steady flow. Due to the reversing flow direction, there are two thermal entrance regions for oscillating flow. The length-averaged Nusselt number for oscillating flow is higher than that for steady flow. The length-averaged Nusselt number for both steady and oscillating flows increase linearly with a dimensionless grouping parameter k*/kfDe/L1/2Pe*1/2. The porous channel heat sink subjected to oscillating flow can be considered as an effective method for cooling high-speed electronic devices.

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