Research on the Hydrodynamic Forces of the Torsional Wave Propulsion by Extended Large-Amplitude Elongated-Body Theory

2011 ◽  
Vol 127 ◽  
pp. 379-384
Author(s):  
De Feng Du ◽  
Xiao Qin Jiang
Keyword(s):  
Swimming Speed ◽  
Wave Speed ◽  
Hydrodynamic Force ◽  
Torsional Wave ◽  
Wave Number ◽  
Dorsal Fin ◽  
Transversal Wave ◽  
Fin Ray ◽  
Wave Numbers ◽  
Body Theory

Torsional wave propulsion is different from transversal wave propulsion. Based on the characteristic feature of fin ray’s motion, we divide the dorsal fin along the radial direction into a series of long narrow bands. For each band, the analysis method is the same as the method computing hydrodynamic force of transversal wave propulsion. Then we give an integral calculation over fin ray’ length. We analyze the influence of the swing amplitude, frequency and length of fin as well as wave numbers and ratio of wave speed to swimming speed on hydrodynamic force. The calculated results show that: 1. the average thrust on the dorsal fin is directly proportional to the square of swing amplitude and frequency of fin ray. 2. The average thrust on the dorsal fin is directly proportional to the biquadrate of ray’s length. 3. As the wave numbers increase, the average thrust begins with a little increase and then turns to decrease. When the wave number roughly equals to 1.5, it reaches to a maximum. 4. If the fin frequency is fixed, the average thrust is of maximum when the ratio of wave speed to swimming speed roughly equals to 1.4.

Stability of Mixed Convection in a Differentially Heated Vertical Channel

1998 ◽  
Vol 120 (1) ◽  
pp. 127-132 ◽  
Author(s):  
Y.-C. Chen ◽  
J. N. Chung
Keyword(s):  
Reynolds Number ◽  
Prandtl Number ◽  
Mixed Convection ◽  
Local Minimum ◽  
Wave Speed ◽  
Vertical Channel ◽  
Shear Instability ◽  
Wave Number ◽  
Wave Numbers ◽  
Prandtl Numbers

In this study, the linear stability of mixed convection in a differentially heated vertical channel is investigated for various Prandtl numbers. The results indicate that this fully developed heated flow can become unstable under appropriate conditions. It is found that both the Prandtl number and Reynolds number hold very important effects on the critical Grashof number, wave number, wave speed, and instability mechanism for higher Prandtl numbers. For low Prandtl numbers, the effects from the Prandtl number and Reynolds number are relatively small. The most significant finding is that the local minimum wave numbers can be as high as eight for Pr = 1000, which is substantially higher than those found before for other heated flows. The existence of multiple local minimum wave numbers is responsible for the sudden jumps of the critical wave number and wave speed and the sudden shift of instability type for higher Prandtl numbers. The energy budget analysis shows that the thermal-shear and shear instabilities dominate at both low and high Reynolds numbers for Pr = 0.7 and 7. It is the thermal-buoyant instability for Re < 1365 and shear instability for Re ≥ 1365 for Pr = 100. The thermal-buoyant and mixed instabilities are the possible instability types for Pr = 1000. In general, for mixed convection channel flows, the instability characteristics of differentially heated flows are found to be substantially different from those of uniformly heated flows.

Infrared spectra and substituent effects in 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones

1983 ◽  
Vol 48 (2) ◽  
pp. 586-595 ◽  
Author(s):  
Alexander Perjéssy ◽  
Pavol Hrnčiar ◽  
Ján Šraga
Keyword(s):  
Substituent Effects ◽  
Phenyl Group ◽  
Wave Number ◽  
Vibrational Coupling ◽  
Wave Numbers ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
The Relationship ◽  
Derivatives Of ◽  
Effect Of Structure

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.

Note on the swimming of slender fish

1960 ◽  
Vol 9 (2) ◽  
pp. 305-317 ◽  
Author(s):  
M. J. Lighthill
Keyword(s):  
Swimming Speed ◽  
Critical Value ◽  
Slender Body ◽  
Vortex Wake ◽  
Frictional Drag ◽  
Slender Body Theory ◽  
Propulsive Efficiency ◽  
Deformable Bodies ◽  
Work Done ◽  
Body Theory

The paper seeks to determine what transverse oscillatory movements a slender fish can make which will give it a high Froude propulsive efficiency, $\frac{\hbox{(forward velocity)} \times \hbox{(thrust available to overcome frictional drag)}} {\hbox {(work done to produce both thrust and vortex wake)}}.$ The recommended procedure is for the fish to pass a wave down its body at a speed of around $\frac {5} {4}$ of the desired swimming speed, the amplitude increasing from zero over the front portion to a maximum at the tail, whose span should exceed a certain critical value, and the waveform including both a positive and a negative phase so that angular recoil is minimized. The Appendix gives a review of slender-body theory for deformable bodies.

scholarly journals Microglanis carlae, a new species of bumblebee catfish (Siluriformes: Pseudopimelodidae) from the río Paraguay basin in Paraguay

2008 ◽  
Vol 6 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Héctor S. Vera Alcaraz ◽  
Weferson J. da Graça ◽  
Oscar A. Shibatta
Keyword(s):  
New Species ◽  
Species Complex ◽  
Anterior Margin ◽  
Color Pattern ◽  
Caudal Peduncle ◽  
Dorsal Fin ◽  
Fin Ray ◽  
Pectoral Spine ◽  
Adipose Fin ◽  
A New Species

Microglanis carlae, new species, is described from the río Paraguay basin and distinguished from its congeners by the following combination of characters: paired and anal fins mottled or with thin faint bands, trunk with dark-brown saddles, anterior margin of pectoral spine with serrations retrorse proximally and antrorse distally, tip of pectoral spine as a distinct bony point, continuous portion of lateral line reaching vertical through last dorsal-fin ray, caudal peduncle with irregularly shaped, faint to dark blotch, maxillary barbel surpassing vertical through dorsal-spine origin, and dark bar on posterior flank continuous from base of adipose fin to that of anal fin. The new species is included in the Microglanis parahybae species complex on the basis of color pattern.

Gaidropsarus mauli a new species of three-bearded rockling (Gadiformes, Gadidae) from the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge) and the Biscay Slope (Northeastern Atlantic)

Zootaxa ◽  
2018 ◽  
Vol 4459 (2) ◽  
pp. 301
Author(s):  
MANUEL BISCOITO ◽  
LUIZ SALDANHA
Keyword(s):  
New Species ◽  
Hydrothermal Vent ◽  
Valid Species ◽  
Lucky Strike ◽  
Pectoral Fins ◽  
Dorsal Fin ◽  
Fin Ray ◽  
Mid Atlantic Ridge ◽  
A New Species ◽  
Northeastern Atlantic

Gaidropsarus mauli, new species, is described from the Lucky Strike Hydrothermal vent site (Mid-Atlantic Ridge) and from the Bay of Biscay. It is distinguished from congeners by a combination of characters such as the number of vertebrae, the size of the first dorsal-fin ray, the profile of the head and the shape of the snout, in dorsal view, the size and the position of the eyes, the length of the pelvic fins, the shape of the pectoral fins, and the length of the lateral line. A comparison with the other 13 valid species of the genus is presented. 

scholarly journals A new species of Anchoviella Fowler, 1911 (Clupeiformes: Engraulidae) from the Amazon basin, Brazil

2012 ◽  
Vol 10 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Marina V. Loeb
Keyword(s):  
New Species ◽  
Standard Length ◽  
Posterior Margin ◽  
Amazon Basin ◽  
Head Length ◽  
Estuarine Species ◽  
Dorsal Fin ◽  
Fin Ray ◽  
Upper Jaw ◽  
A New Species

Anchoviella juruasanga is described from the drainages of rios Negro, Madeira, Tapajós, Trombetas, Tocantins, and Jari, in the Amazon basin, Brazil. The new species is distinguished from its congeners by having a short upper jaw, with its posterior tip extending between the verticals through anterior and posterior margins of the pupil (vs. posterior tip of upper jaw extending beyond the vertical through posterior margin of the pupil). Anchoviella juruasanga is also distinct from other strictly freshwater Amazonian species of the genus by the distance from tip of snout to posterior end of upper jaw between 8 and 11% in standard length (vs. 14% or more in A. alleni, A. carrikeri, A. guianensis, and A. jamesi). The anal-fin origin slightly posterior to or at the vertical through the base of the last dorsal-fin ray further distinguishes the new species from A. alleni (anal-fin origin posterior to the vertical through the last anal-fin ray by at least 14% of head length) and A. jamesi (anal-fin origin anterior to the vertical through the last anal-fin ray). An identification key for the Amazonian species of Anchoviella, including marine and estuarine species known to occur in the lower portion of the basin, is presented.

scholarly journals The band spectrum of hydrogen

1924 ◽  
Vol 106 (735) ◽  
pp. 69-82 ◽  
Keyword(s):  
Molecular Hydrogen ◽  
Hydrogen Molecule ◽  
Spectral Lines ◽  
Wave Number ◽  
Band Spectrum ◽  
Wave Numbers ◽  
Experimental Side ◽  
The Subject ◽  
The Moment ◽  
Theoretical Side

Many attempts have been made to detect regularities amongst the numerous lines which constitute the secondary or many-lined spectrum of hydrogen. The extreme complexity of the spectrum may be realised from the fact that in the Bakerian Lecture of 1922 Merton and Barratt record some 750 lines in the interval between Hα (wave-number v = 5233.216) and Hβ ( v = 20564.793). Three methods of investigation may be employed in the search for regularities. (1) The lines may be classified according to their physical characteristics, such as intensity or mode of excitation, as in the tables of Merton and Barrat ( loc. cit .). (2) Lines may be grouped together by the discovery of relations between their wave-lengths or wave-numbers, as in the important groups of lines which have been arranged in bands by Fulcher. (3) Lastly, the question may be attacked from the theoretical side, and a model of the hydrogen molecule may be imagined, which will give rise to the emission of certain characteristic spectral lines. Thus Sutherland, working on the foundation of the classical mechanical laws, more than twenty years ago, came to the conclusion that spectral series must arise from kinematical considera­tions, and explained them by considering the nodal sub-divisions of a circle. At the present time we may expect more successful results to follow from the application of the quantum theory, and in this paper an endeavour will be made to examine the secondary spectrum of hydrogen, and more particularly the Fulcher bands, from this standpoint. I may add that my interest in the subject was aroused when attempting to construct a model of the hydrogen molecule, for it seemed that the most likely method of obtaining reliable information from the experimental side as to the moment of inertia of the molecule would be from a study of the spectrum of molecular hydrogen.

scholarly journals Scorpaena decemradiata new species (Teleostei: Scorpaenidae) from the Gulf of Aqaba, northern Red Sea, a species distinct from Scorpaena porcus

2018 ◽  
Vol 82 (3) ◽  
pp. 169
Author(s):  
Ronald Fricke ◽  
Daniel Golani ◽  
Brenda Appelbaum-Golani ◽  
Uwe Zajonz
Keyword(s):  
New Species ◽  
Red Sea ◽  
Gulf Of Aqaba ◽  
Pectoral Fin ◽  
Dorsal Fin ◽  
Lower Jaw ◽  
Fin Ray ◽  
Fin Rays ◽  
Northern Red Sea ◽  
Scorpaena Porcus

The scorpionfish Scorpaena decemradiata n. sp. is described from off the coast of Israel in the Gulf of Aqaba, northern Red Sea. The new species is similar to S. porcus Linnaeus, 1758, but is characterized by dorsal fin spines XII, soft dorsal fin rays 10 (the last divided at base); pectoral fin rays 16, uppermost branched pectoral fin ray is the second; lacrimal with 2 spines over maxilla that point at nearly right angle from each other, the posterior pointing ventrally and slightly anteriorly; occipital pit well developed; anteriormost mandibular lateral-line pores small, separated; scales ctenoid; 59-62 scale rows in longitudinal series; scales absent on chest and pectoral fin base; and cirri developed over entire head and body, but no cirri on lower jaw. An updated checklist of the species of the genus Scorpaena Linnaeus, 1758 and a key to the species of the eastern Atlantic, Mediterranean Sea and Red Sea are presented.

Bio-Inspired Robotic Undulatory Stingray

2016 ◽  
Author(s):  
Emily Studebaker ◽  
William Ermlick ◽  
Rickey Warner ◽  
Brandon Hart ◽  
Aanand Pandey ◽  
...  
Keyword(s):  
Qualitative Agreement ◽  
Wave Speed ◽  
Wave Amplitude ◽  
Wave Number ◽  
Computational Results ◽  
Cfd Simulations ◽  
Amplitude Wave ◽  
And Control ◽  
Undulating Fin

The purpose of this study was to investigate fin undulation as a form of locomotion. The analysis generated CFD simulations and models that identify characteristics that are known to indicate propulsive forces. A mechanical undulating fin was designed and built to experimentally validate these computational results. Comparing thrust data from the mechanical fin with the CFD results yielded qualitative agreement with various parameters including wave amplitude, wave speed, and wave number. Quantifying these characteristics are necessary towards understanding the mechanics of undulation and will aid in the design and control of underwater undulating robotics.

scholarly journals A new species of the loricariid catfish genus Hemipsilichthys from southern Rio de Janeiro coastal rivers, southeastern Brazil (Teleostei: Siluriformes)

Zootaxa ◽  
2003 ◽  
Vol 285 (1) ◽  
pp. 1 ◽  
Author(s):  
EDSON H.L. PEREIRA ◽  
ROBERTO E. REIS ◽  
PABLO F.M. SOUZA ◽  
HENRIQUE LAZZAROTTO
Keyword(s):  
New Species ◽  
Rio De Janeiro ◽  
Close Relationships ◽  
Southeastern Brazil ◽  
Southern Coast ◽  
Dorsal Fin ◽  
Fin Ray ◽  
Coastal Rivers ◽  
A New Species ◽  
Janeiro State

Hemipsilichthys nimius, new species, is described from the upper Perequê-Açu River in Parati, in the southern coast of Rio de Janeiro State, southeastern Brazil. The new species is distinguished from the remaining 18 Hemipsilichthys species by modally having eight branched rays in the dorsal fin (vs. seven branched rays), by possessing a posteriorly expanded dorsal-fin membrane connecting the last dorsal-fin ray to the dorsum and, except from H. gobio and H. papillatus, by having teeth cusps equal in size (vs. small lateral cusp or unicuspid teeth in both dentary and premaxilla). From H. gobio and H. papillatus it is further distinguished by the larger orbital diameter and by its V-shaped dorsal-fin spinelet. Hemipsilichthys nimius shares with H. gobio and H. papillatus several characters that might be indicative of close relationships. These putative phylogenetic relationships are discussed.

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