The Effects of an Air/Water Surface on the Fast-Start Performance of Rainbow Trout (Oncorhynchus Mykiss)

1991 ◽  
Vol 155 (1) ◽  
pp. 219-226 ◽  
Author(s):  
PAUL W. WEBB ◽  
DOMINIQUE SIMS ◽  
WILLIAM W. SCHULTZ
Keyword(s):  
Rainbow Trout ◽  
Water Depth ◽  
Water Surface ◽  
The Body ◽  
Energy Dispersion ◽  
Cumulative Distance ◽  
Relative Water ◽  
Fast Start ◽  
Turning Radius ◽  
Water Depths

Fast-start performance of rainbow trout (mass 0.187±0.022kg; mean±2S.E., N= 10) was measured in water of various depths. Relative water depth was defined as z/B, where z is the water depth measured from the air/water surface to the longitudinal midline of the body and B is the span of the caudal fin, 0.062±0.004m. Relative water depths (at absolute depths) tested were; 0.31 (at 0.05m), 1.11 (at 0.1m), 1.92 (at 0.15m), 2.73 (at 0.2m) and 7.56 (at 0.5m). Performance was defined in terms of the motion of the centre of mass as measured by the turning radius and the cumulative distance travelled in a given elapsed time. Turning radius was not affected by water depth and averaged 0.018±0.003m. Distance travelled was a positive function of water depth, although paired t-tests showed no significant effect of depth at 0.15 and 0.2 m after about 70 ms. Energy dispersion due to the formation of surface waves increased with decreasing relative water depth. The largest energy dispersion in wave formation at a relative water depth of 0.31 averaged about 70% of the useful mechanical work performed in deep water. Energy dispersion in wave generation was negligible for relative water depths larger than approximately 3. Energy dispersion is similar to that for rigid streamlined bodies moving at constant speed

The effect of size on the fast-start performance of rainbow trout Salmo gairdneri, and a consideration of piscivorous predator-prey interactions

1976 ◽  
Vol 65 (1) ◽  
pp. 157-177 ◽  
Author(s):  
P. W. Webb
Keyword(s):  
Rainbow Trout ◽  
Reaction Time ◽  
Reaction Times ◽  
The Body ◽  
Salmo Gairdneri ◽  
Escape Behaviour ◽  
Predator Prey ◽  
Average Value ◽  
Fast Start ◽  
Prey Escape

The fast-start (acceleration) performance of seven groups of rainbow trout from 9-6 to 38-7 cm total length was measured in response to d.c. electric shock stimuli. Two fast-start kinematic patterns, L- and S-start were observed. In L-starts the body was bent into an L or U shape and a recoil turn normally accompanied acceleration. Free manoeuvre was not possible in L-starts without loss of speed. In S-starts the body was bent into an S-shape and fish accelerated without a recoil turn. The frequency of S-starts increased with size from 0 for the smallest fish to 60–65% for the largest fish. Acceleration turns were common. The radius of smallest turn for both fast-start patterns was proportional to length (L) with an overall radius of 0–17 L. The duration of the primary acceleration stages increased with size from 0–07 s for the group of smallest fish to 0–10 s for the group of largest fish. Acceleration rates were independent of size. The overall mean maximum rate was 3438 cm/s2 and the average value to the end of the primary acceleration movements was 1562 cm/s2. The distance covered and velocity attained after a given time for fish accelerating from rest were independent of size. The results are discussed in the context of interactions between a predator and prey fish following initial approach by the predator. It is concluded that the outcome of an interaction is likely to depend on reaction times of interacting fish responding to manoeuvres initiated by the predator or prey. The prey reaction time results in the performance of the predator exceeding that of the prey at any instant. The predator reaction time and predator error in responses to unpredictable prey manoeuvre are required for prey escape. It is predicted that a predator should strike the prey within 0-1 s if the fish are initially 5–15 cm apart as reported in the literature for predator-prey interactions. These distances would be increased for non-optimal prey escape behaviour and when the prey body was more compressed or depressed than the predator.

scholarly journals Disc starts: the pectoral disc of stingrays promotes omnidirectional fast starts across the substrate

2019 ◽  
Vol 97 (7) ◽  
pp. 597-605 ◽  
Author(s):  
S.G. Seamone ◽  
T.M. McCaffrey ◽  
D.A. Syme
Keyword(s):  
Rigid Body ◽  
The Body ◽  
Similar Performance ◽  
Yaw Rate ◽  
Benthic Environment ◽  
Fast Start ◽  
Escape Responses ◽  
Turning Radius ◽  
Longitudinal Flexibility ◽  
Translational Speed

We explored how the flattened and rounded pectoral disc of the ocellate river stingray (Potamotrygon motoro (Müller and Henle, 1841)) enables them to use the benthic plane during fast-start escape. Escape responses were elicited via prodding different locations around the pectoral disc and were recorded using video. Modulation of pectoral-fin movements that power swimming enabled omnidirectional escape across the substrate, with similar performance in all directions of escape. Hence, translation of the body did not necessarily have to follow the orientation of the head, overcoming the constraint of a rigid body axis. An increase in prod speed was associated with an increase in initial translational speed and acceleration away from the prod. As prod location shifted towards the snout, yaw rotation increased, eventually reorienting the fish into a forward swimming position away from the prod. Furthermore, P. motoro yawed with essentially zero turning radius, allowing reorientation of the head with simultaneous rapid translation away from the prod, and yaw rate during escape was substantially greater than reported during routine swimming for stingrays. We conclude that stingrays employ a distinctive approach to escape along the substrate, which we have termed disc starts, that results in effective manoeuvrability across the benthic environment despite limited longitudinal flexibility of the body and that challenges the concept of manoeuvrability typically used for fishes.

On the Performance of an Array of Floating Wave Energy Converters for Different Water Depths

2014 ◽  
Author(s):  
Peter McCallum ◽  
Vengatesan Venugopal ◽  
David Forehand ◽  
Rebecca Sykes
Keyword(s):  
Water Depth ◽  
Wave Energy ◽  
Power Production ◽  
Peak Performance ◽  
Mean Power ◽  
Small Shift ◽  
Wave Energy Converters ◽  
Relative Water ◽  
Water Depths ◽  
Energy Converters

A frequency domain hydrodynamic assessment was carried out using WAMIT on buoy type wave energy converters (WECs), constrained to move in heave only. Control of the power take-off (PTO) system has been established through real control (damping resistance only) for an isolated WEC. This fixed value has then been applied to all WECs in an array of ten devices, set out in two rows. The array has been tested in six water depths, represented by the relative water depth d/λ0, ranging from 0.25 to infinite depth, where λ0 is the resonant wavelength of an isolated WEC in infinitely deep water. Incremental reductions in water depth, result in an drop in peak q̄-factor, which was also marked with a small shift in ka. It was deemed appropriate here to re-tune the PTO settings for the different water depths. The various interactions within the array were examined in more detail by considering the radiation forces between WECs. Results are presented, highlighting the most significant device interactions due to the variations in water depth. The growth and shift in ka of the peak forces are also evident in shallower water. Depth modified JONSWAP and Pierson-Moskowitz spectra have also been applied in order to calculate mean power production estimates for the various water depths. For the particular array and conditions considered, there was a clear downward trend in power captured when moving into progressively shallower water. This was in part due to the reduction in total energy available in the shallower spectra, but also because the frequency of peak performance of the array has shifted significantly.

scholarly journals Improved structure of vertical flow velocity distribution in natural rivers based on mean vertical profile velocity and relative water depth

2017 ◽  
Vol 49 (3) ◽  
pp. 878-892
Author(s):  
S. Song ◽  
B. Schmalz ◽  
N. Fohrer
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
Water Depth ◽  
Vertical Velocity ◽  
Water Surface ◽  
Friction Velocity ◽  
Depth Direction ◽  
Relative Water ◽  
Estimated Error ◽  
New Formula

Abstract Logarithmic, power, and parabolic distribution laws were proven to be efficient for the prediction of vertical velocity distribution. Traditionally, the distribution formulas involve the friction velocity (u*) and the depth (y) of the measurement point. The low availability of friction velocity and limitation of real water depth data hindered the promotion and comparison of the available flow velocity formulas. In this paper, we proposed a new formula structure adopting a relative flow velocity based on mean vertical velocity (u/ū) and dimensionless relative water depth (y/H). The observations showed the following. (1) The substitution of u* and y with u/ū and y/H were reliable and applicable. Parabolic logarithmic and power fitting curves worked well, with an error of 7%, 10%, and 11%, respectively. (2) In water depth direction, the predicted results of the middle depth of the vertical profiles tend to be more reliable and precise. The highest estimated error appeared in the area near the water surface. (3) Higher catchment slope resulted in larger coefficients and constants in logarithmic and power fitting. (4) In the rivers with higher width-to-depth ratio, the maximum profile velocity occurred closer to the water surface, and mean profile velocity tended to happen more at the bottom.

Competition of Class I and II Instabilities in Evolution of Crescent Waves

2013 ◽  
Author(s):  
Kai Yan ◽  
Zhili Zou ◽  
Yalong Zhou
Keyword(s):  
Water Depth ◽  
Wave Pattern ◽  
Linear Instability ◽  
Stokes Wave ◽  
Wave Steepness ◽  
Wave Basin ◽  
Relative Water ◽  
Wave Trains ◽  
Linear Instability Analysis ◽  
Water Depths

A laboratory experiment on the instability of Stokes wave trains with large steepness in finite water depths in a wave basin is performed. Two class instabilities of Stokes wave, quartet interaction and quintet interaction, were observed, and it is found that the evolution of crescent wave pattern is affected by the development of quintet interaction. The dependence of this effect on relative water depth was analyzed. The wave steepness for the occurrence of the competition is examined by applying linear instability analysis of Stokes wave.

scholarly journals Microplastic contamination of the drilling bivalve Hiatella arctica in Arctic rhodolith beds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Teichert ◽  
Martin G. J. Löder ◽  
Ines Pyko ◽  
Marlene Mordek ◽  
Christian Schulbert ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Water Depth ◽  
The Arctic ◽  
Polymer Composition ◽  
Bivalve Species ◽  
Filter Feeder ◽  
Hiatella Arctica ◽  
Long Term Consequences ◽  
Water Depths

AbstractThere is an increasing number of studies reporting microplastic (MP) contamination in the Arctic environment. We analysed MP abundance in samples from a marine Arctic ecosystem that has not been investigated in this context and that features a high biodiversity: hollow rhodoliths gouged by the bivalve Hiatella arctica. This bivalve is a filter feeder that potentially accumulates MPs and may therefore reflect MP contamination of the rhodolith ecosystem at northern Svalbard. Our analyses revealed that 100% of the examined specimens were contaminated with MP, ranging between one and 184 MP particles per bivalve in samples from two water depths. Polymer composition and abundance differed strongly between both water depths: samples from 40 m water depth showed a generally higher concentration of MPs and were clearly dominated by polystyrene, samples from 27 m water depth were more balanced in composition, mainly consisting of polyethylene, polyethylene terephthalate, and polypropylene. Long-term consequences of MP contamination in the investigated bivalve species and for the rhodolith bed ecosystem are yet unclear. However, the uptake of MPs may potentially impact H. arctica and consequently its functioning as ecosystem engineers in Arctic rhodolith beds.

scholarly journals Production and water yield of cauliflower under irrigation depths and nitrogen doses

2019 ◽  
Vol 23 (8) ◽  
pp. 561-565
Author(s):  
Reginaldo M. de Oliveira ◽  
Rubens A. de Oliveira ◽  
Sanzio M. Vidigal ◽  
Ednaldo M. de Oliveira ◽  
Lorença B. Guimarães ◽  
...  
Keyword(s):  
Water Depth ◽  
Irrigation Water ◽  
Water Yield ◽  
Crop Evapotranspiration ◽  
Fresh Weight ◽  
Randomized Design ◽  
Mean Diameter ◽  
Irrigation Depth ◽  
Completely Randomized Design ◽  
Water Depths

ABSTRACT Cauliflower is a brassica produced and consumed in Brazil, whose cultivation depends on the adequate supply of water and nutrients. The objective of this study was to evaluate the effect of irrigation depths and nitrogen doses on the production components and water yield of cauliflower hybrid Barcelona CMS. The treatments consisted of five irrigation water depths (0, 75, 100, 125 and 150% of the crop evapotranspiration) combined with five nitrogen doses (0, 75, 150, 300 and 450 kg ha-1). The experiment was conducted in a completely randomized design with a split-plot arrangement. The effects of these factors were evaluated using the response surface methodology. The water yield of the crop decreases with increasing irrigation water depth; therefore, the yield is higher when water replenishment is lower than the recommended. The highest estimated total inflorescence yield is 24,547.80 kg ha-1, with a inflorescence mean diameter of 19.60 cm, a inflorescence mean height of 12.25 cm, and an inflorescence fresh weight of 858.90 g plant-1, obtained with an irrigation water depth equivalent to 132.09% of the crop evapotranspiration (ETc) and a nitrogen dose of 450 kg ha-1. The highest inflorescence diameter and height are obtained with an irrigation depth equivalent to 128.70 and 108.20% of ETc, respectively, and a nitrogen dose of 450 kg ha-1. Therefore, the best productivity response of the Barcelona CMS cauliflower hybrid can be obtained using an irrigation depth greater than the crop evapotranspiration, regardless of the nitrogen doses.

Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

2021 ◽  
pp. 147509022110313
Author(s):  
T J Jemi Jeya ◽  
V Sriram ◽  
V Sundar
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Scattering Parameter ◽  
Oblique Waves ◽  
Test Conditions ◽  
Relative Water ◽  
Identical Test ◽  
Run Up ◽  
Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

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