WATER FLOWS AROUND THE COMB PLATES OF THE CTENOPHORE PLEUROBRACHIA PLOTTED BY COMPUTER: A MODEL SYSTEM FOR STUDYING PROPULSION BY ANTIPLECTIC METACHRONISM

1993 ◽  
Vol 177 (1) ◽  
pp. 113-128 ◽  
Author(s):  
D. Barlow ◽  
M. A. Sleigh ◽  
R. J. White
Keyword(s):  
Computer Program ◽  
Water Flow ◽  
High Speed ◽  
Beat Frequency ◽  
Longitudinal Axis ◽  
Model System ◽  
The Other ◽  
Contour Maps ◽  
Water Flows ◽  
Pleurobrachia Pileus

Patterns of water flow around steadily beating comb plates of Pleurobrachia pileus were tracked using suspended plastic beads. The positions of the beads and the comb plates in the plane of the central longitudinal axis of the comb row were digitised from high-speed cine films covering several beat cycles. All of the data from each sequence were combined using a computer program which integrated them into a standard cycle, and the resulting data were plotted by a second computer program to produce charts for different stages in the beat cycle showing the flow velocity at a grid of points. On these charts, contour maps were drawn to indicate the speed and direction of the water flow. Water is drawn towards each comb row from ahead and from the sides and accelerates strongly backwards in a fairly narrow stream which joins those from the other seven comb rows at the rear of the animal. At a beat frequency of 10 Hz the comb plates move with a tip speed of up to 70 mm s-1 in their effective stroke; they have an estimated Reynolds number of 9 in this stroke. Changes in inter- plate volume between adjacent antiplectically coordinated plates are very important in propulsion, particularly near the end of the effective stroke when pairs of adjacent plates close together and cause the high-speed water from around the ciliary tips to be shed into the overlying stream as a series of jets at speeds of 50 mm s-1 or more. The antiplectic coordination of the comb plates makes a major contribution to the efficiency of propulsion.

scholarly journals X-Ray CT inspection of subsurface areas of concretes exposed to fast flowing liquids

2019 ◽  
Vol 2 (1) ◽  
pp. 450-459 ◽  
Author(s):  
Libor Sitek ◽  
Petr Hlaváček ◽  
Kamil Souček ◽  
Lenka Bodnárová ◽  
Josef Foldyna ◽  
...  
Keyword(s):  
Water Flow ◽  
High Speed ◽  
Pure Water ◽  
Hardened Cement ◽  
X Ray ◽  
Mechanical Simulation ◽  
Water Flows ◽  
Whole Process ◽  
Long Time ◽  
Complex Phenomena

Abstract Concrete structures affected for a long time by flowing liquids are exposed to gradual erosion in surface layers caused by a combination of several degradation processes: abrasion, cavitation and chemical or bacterial impacts. Due to the complex phenomena and difficult-to-define initial and boundary conditions, the whole process cannot be easily simulated using the conventional computing tools. Laboratory experimental research is thus the most appropriate approach for the investigation of a suitable composition of concrete resistant to the flowing liquids. However, the methods used are often very time consuming and last even several years. High-speed water flows can be elegantly used for the acceleration of the mechanical simulation of a real situation. Several experiments on the effects of the high-speed water flows on concrete surfaces have been carried out. Using the X-Ray CT methods, subsurface structures of concretes exposed to the accelerated mechanical simulation of the erosion wear caused by fast flowing liquids were investigated and presented in the article. It has been shown that the simulation does not cause initiation of new fractures or cracks in the original concrete structure. The pure water flow mainly removes the hardened cement paste and reveals the aggregate grains. The water flow with abrasive particles disintegrates in greater depths and washes out entire aggregate grains, eventually amputates them and finally smoothens entire surface.

Research on Balancing of a Multi-Link High-Speed Precision Press

2013 ◽  
Vol 567 ◽  
pp. 175-182
Author(s):  
Xin Jian Lu ◽  
Si Hong Zhu ◽  
Lei Kang ◽  
Mao Hua Xiao
Keyword(s):  
Computer Program ◽  
High Speed ◽  
Kinetic Equations ◽  
Inertial Force ◽  
The Other ◽  
Inertial Forces ◽  
Software Environment ◽  
The Press ◽  
Calculation Results ◽  
The One

Balancing mechanism for a multi-link high-speed precision press has been proposed and kinetic equations for the press with balancing mechanism have been derived also. The corresponding computer program has been developed on the basis of Matlab software environment. Take the press developed in the research as an example to calculate for studying balancing effect of this mechanism. Calculation results show that the balancing mechanism can significantly reduce vertical inertial force acted on the bed on the one hand; on the other hand the horizontal inertial forces of some parts and torque need will be increased. Results of the research mentioned above can be used for development of the multi-link high-speed precision press.

Spray Generated by an Airblast Atomizer at High-Pressure Conditions

2007 ◽  
Author(s):  
Feras Z. Batarseh ◽  
Ilia V. Roisman ◽  
Cam Tropea
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Velocity Vector ◽  
Ambient Pressure ◽  
Air Flow ◽  
Water Flow Rate ◽  
The Other ◽  
Air Flow Rate ◽  
Spray Visualization

We present an experimental investigation of a spray generated by an airblast atomizer. Experiments have been performed in a pressure chamber equipped by transparent windows allowing an optical access to the spray. Several techniques of spray investigation have been applied: spray visualization using the high-speed video system, spray visualization and instantaneous velocity measurements using the PIV technique, spray velocimetry and sizing using the IPI and phase Doppler instruments. Phase Doppler instrument has been used to characterize the droplets in the spray: their diameter, two components of the velocity vector. Also the integral parameters of the spray, such as the local volume flux density, have been characterized. We conduct a parametric study of the effect of the ambient pressure, the air flow rate and the water flow rate on an atomized spray. Measurements at different radial locations in the spray and in two planes were performed. The measurements in these two planes allow one to determine the distributions of all the three components of the average drop velocity vector: axial, radial and azimuthal. PDA measurements show that atomized spray is sensitive to any change in the studied parameters. For example, increasing air flow rate from 20 SCMH to 45 SCMH and keeping same water flow rate and pressure, leads to an increase in all velocity components and also to a change in droplets diameters. On the other hand, keeping constant pressure and air flow rate and increasing water flow rate from 0.7 to 1.4 l/hr, leads to an increase in water droplets sizes and the axial velocity component, whereas the other velocity components show a non uniform change. Moreover, increasing the ambient pressure leads to the growth of the spray velocity and drops diameters.

scholarly journals Metachronal rhythms and gill movements of the nymph of caenis horaria (Ephemeroptera) in relation to water flow

1934 ◽  
Vol 115 (791) ◽  
pp. 30-48 ◽  
Keyword(s):  
Water Flow ◽  
Phase Difference ◽  
Surrounding Medium ◽  
Axial Flow ◽  
Longitudinal Axis ◽  
The Body ◽  
The Other

The gills of some Ephemerid nymphs are always motionless, e. g ., many Bætine forms of English streams. In many others, however, the gills move rapidly in metachronal rhythm, by virtue of which currents are created in the water. These currents are peculiar to the species and probably have an adaptational significance. In many forms already under investigation, e. g ., Cholen dipterum. Siphlurus sp. Ecdyonurus venosus, Ephemerella sp. Leptophlebia marginata and Ephemera vulgata , a common feature is noticeable. This is that in their rhythmical movements both members of each pair of gills beat together, i. e ., and their movements are co-phasedly synchronized. Since, therefore, the effect of the gills on one side of the body is exactly duplicated on the other, whatever may be the precise mechanism for the production of currents, the latter are symmetrical with the longitudinal axis of the body (Eastham, 1932). An intersting exception in the nymph of Caenis horaria . In this animal the currents pass over the body from one side to the other. The gills beat in metachronal rhythm down each side of the body, but though the rhythms are synchronous there is a time phase difference between them. In other words, members of a pair are not co-phasedly synchronized in movement. We have thus in Caenis horaria a bi-laterally symmetrical animal producing movements in the surrounding medium which are not of the nature of an axial flow. It is with this phenomenon that this paper deals.

Estimation of the virtual water trade between two Spanish regions: Castilla-la Mancha and Murcia

2010 ◽  
Vol 10 (5) ◽  
pp. 831-840 ◽  
Author(s):  
Ángel De Miguel ◽  
Eloy García ◽  
Irene De Buestamante
Keyword(s):  
Water Flow ◽  
Food Processing ◽  
Virtual Water ◽  
Water Transfer ◽  
Water Efficiency ◽  
International Context ◽  
Water Flows ◽  
Spanish Regions ◽  
La Mancha ◽  
Virtual Water Flow

Virtual water is defined as the water needed to produce a product. We can use virtual water flow calculations to estimate the water efficiency of a country, as well as its economic dependence on water resources. Former studies on this area have focused on quantifying the virtual water flows between countries, in an international context. In this study we reduce the action framework to regions within a country, determining the virtual water balance between two Spanish regions: Castilla-La Mancha and Murcia. In 2004, Castilla-La Mancha exported to Murcia 2,453,442 tons of commercial products, from which 1,191,628 tons were agricultural goods. In terms of virtual water, it means 1,365 hm3, including food-processing, and industrial products. It is necessary to add 350 hm3 to the result, because of the water transfer (Tajo-Segura transfer) between the rivers basins of these regions, so the final virtual water number, in 2004, was 1,715 hm3. The other way round, Murcia exported in 2004 2,069,000 tons of products, from which 490,351 tons were agricultural goods. That supposes 712 hm3 of virtual water. Virtual water flow is unbalanced and displaced towards Murcia with a difference of 1,003 hm3.

scholarly journals Seat pitch and comfort of a staggered seat configuration

Work ◽  
2021 ◽  
Vol 68 (s1) ◽  
pp. S151-S159
Author(s):  
Zhihui Liu ◽  
T. Rotte ◽  
S. Anjani ◽  
P. Vink
Keyword(s):  
Longitudinal Axis ◽  
The Other ◽  
Sitting Position ◽  
Lateral Direction ◽  
Top View ◽  
Design Freedom ◽  
Cabin Interior ◽  
Physical Dimensions

BACKGROUND: Staggered seats are a solution for the Flying-V aircraft, where the cabin’s longitudinal axis has a 26 degrees angle with respect to the direction of flight, to compensate for an otherwise oblique sitting position. However, little is known on acceptable pitches in this staggered configuration. OBJECTIVE: The goal of this research is to evaluate the comfort of different pitches for seats that are staggered relative to the cabin’s longitudinal axis. METHODS: Two rows of staggered seats are positioned at three different pitches (27, 29 and 31 inches). 53 participants were seated in each setup. For each, a questionnaire was completed including questions on comfort and discomfort, top view photos were taken to analyse postures and physical dimensions were recorded to define passengers’ space. RESULTS: Comfort as well as discomfort were significantly different for the three setups. The comfort at 27 inches was seen as unacceptably low. The 29 and 31-inch configurations showed to result in acceptable levels of comfort, comparable to higher-end seating layouts. There were very little complaints about space in lateral direction (elbow and seat width), showing the advantage of having your won armrest and shoulder space in the staggered configuration. Interesting was that at larger pitches more complaints were found for the seat characteristics, probably in the shorter pitch the other discomfort was overruling this. CONCLUSION: The 26-degree staggered configuration offers improvements in shoulder- and elbow-space. The results for the 29- and 31-inch are expected to allow enough design freedom for further exploration of such a configuration for the Flying-V cabin interior.

scholarly journals Leader-chasing behavior in negative artificial triggered lightning flashes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fukun Wang ◽  
Jianguo Wang ◽  
Li Cai ◽  
Rui Su ◽  
Wenhan Ding ◽  
...  
Keyword(s):  
High Speed ◽  
The Other ◽  
Lightning Flash ◽  
High Speed Camera ◽  
Return Stroke ◽  
Catching Up ◽  
Special Cases ◽  
Triggered Lightning

AbstractTwo special cases of dart leader propagation were observed by the high-speed camera in the leader/return stroke sequences of a classical triggered lightning flash and an altitude-triggered lightning flash, respectively. Different from most of the subsequent return strokes preceded by only one leader, the return stroke in each case was preceded by two leaders occurring successively and competing in the same channel, which herein is named leader-chasing behavior. In one case, the polarity of the latter leader was opposite to that of the former leader and these two combined together to form a new leader, which shared the same polarity with the former leader. In the other case, the latter leader shared the same polarity with the former leader and disappeared after catching up with the former leader. The propagation of the former leader in this case seems not to be significantly influenced by the existence of the latter leader.

Experimental Characterization of a Modified Airlift Pump

2014 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Keegan Fernandes
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Water Flow Rate ◽  
High Speed Photography ◽  
Two Phase ◽  
Inner Diameter ◽  
Airlift Pump ◽  
Flow Map ◽  
Churn Flow

This paper presents an experimental investigation on a modified airlift pump. Experiments were undertaken as a function of air-water flow rate for two submergence ratios (ε=0.58 and 0.74), and two different riser geometries (i) straight pipe with a constant inner diameter of 19 mm and (ii) enlarged pipe with a sudden expanded diameter of 19 to 32 mm. These transparent vertical pipes, of 1 m length, were submerged in a transparent rectangular tank (0.45×0.45×1.1 m3). The compressed air was injected into the vertical pipe to lift the water from the reservoir. The flow map regime is established for both configurations and compared with previous studies. The two phase air-water flow structure at the expansion region is experimentally characterized. Pipeline geometry is found to have a significant influence on the output water flow rate. Using high speed photography and electrical conductivity probes, new flow regimes, such as “slug to churn” and “annular to churn” flow, are observed and their influence on the output water flow rate and efficiency are discussed. These experimental results provide fundamental insights into the physics of modified airlift pump.

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