Journal articles: 'Edge velocity'

1

Anagaw, Amsalu Y., and Mauricio D. Sacchi. "Edge-preserving smoothing for simultaneous-source full-waveform inversion model updates in high-contrast velocity models." GEOPHYSICS 83, no. 2 (March 1, 2018): A33—A37. http://dx.doi.org/10.1190/geo2017-0563.1.

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Full-waveform inversion (FWI) can provide accurate estimates of subsurface model parameters. In spite of its success, the application of FWI in areas with high-velocity contrast remains a challenging problem. Quadratic regularization methods are often adopted to stabilize inverse problems. Unfortunately, edges and sharp discontinuities are not adequately preserved by quadratic regularization techniques. Throughout the iterative FWI method, an edge-preserving filter, however, can gently incorporate sharpness into velocity models. For every point in the velocity model, edge-preserving smoothing assigns the average value of the most uniform window neighboring the point. Edge-preserving smoothing generates piecewise-homogeneous images with enhanced contrast at boundaries. We adopt a simultaneous-source frequency-domain FWI, based on quasi-Newton optimization, in conjunction with an edge-preserving smoothing filter to retrieve high-contrast velocity models. The edge-preserving smoothing filter gradually removes the artifacts created by simultaneous-source encoding. We also have developed a simple model update to prevent disrupting the convergence of the optimization algorithm. Finally, we perform tests to examine our algorithm.

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Reif, Dylan W., Howard B. Bluestein, Tammy M. Weckwerth, Zachary B. Wienhoff, and Manda B. Chasteen. "Estimating the Maximum Vertical Velocity at the Leading Edge of a Density Current." Journal of the Atmospheric Sciences 77, no. 11 (November 2020): 3683–700. http://dx.doi.org/10.1175/jas-d-20-0028.1.

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AbstractThe maximum upward vertical velocity at the leading edge of a density current is commonly <10 m s−1. Studies of the vertical velocity, however, are relatively few, in part owing to the dearth of high-spatiotemporal-resolution observations. During the Plains Elevated Convection At Night (PECAN) field project, a mobile Doppler lidar measured a maximum vertical velocity of 13 m s−1 at the leading edge of a density current created by a mesoscale convective system during the night of 15 July 2015. Two other vertically pointing instruments recorded 8 m s−1 vertical velocities at the leading edge of the density current on the same night. This study describes the structure of the density current and attempts to estimate the maximum vertical velocity at their leading edges using the following properties: the density current depth, the slope of its head, and its perturbation potential temperature. The method is then be applied to estimate the maximum vertical velocity at the leading edge of density currents using idealized numerical simulations conducted in neutral and stable atmospheres with resting base states and in neutral and stable atmospheres with vertical wind shear. After testing this method on idealized simulations, this method is then used to estimate the vertical velocity at the leading edge of density currents documented in several previous studies. It was found that the maximum vertical velocity can be estimated to within 10%–15% of the observed or simulated maximum vertical velocity and indirectly accounts for parameters including environmental wind shear and static stability.

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Vaivads, A., A. Retinò, Yu V. Khotyaintsev, and M. André. "The Alfvén edge in asymmetric reconnection." Annales Geophysicae 28, no. 6 (June 23, 2010): 1327–31. http://dx.doi.org/10.5194/angeo-28-1327-2010.

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Abstract. We show that in the case of magnetic reconnection where the Alfvén velocity is much higher in the plasma on one side of the current sheet than the other, an Alfvén edge is formed. This edge is located between the electron and ion edges on the high Alfvén velocity side of the current sheet. The Alfvén edge forms because the Alfvén wave generated near the X-line will propagate faster than the accelerated ions forming the ion edge. We discuss possible generation mechanism and the polarization of the Alfvén wave in the case when higher Alfvén speed is due to larger magnetic field and smaller plasma density, as in the case of magnetopause reconnection. The Alfvén wave can be generated due to Hall dynamics near the X-line. The Alfvén wave pulse has a unipolar electric field and the parallel current will be such that the outer current on the high magnetic field side is flowing away from the X-line. Understanding Alfvén edges is important for understanding the separatrix regions at the boundaries of reconnection jets. We present an example of Alfvén edge observed by the Cluster spacecraft at the magnetopause.

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NAYAGAM, VEDHA, and F. A. WILLIAMS. "Lewis-number effects on edge-flame propagation." Journal of Fluid Mechanics 458 (May 10, 2002): 219–28. http://dx.doi.org/10.1017/s0022112002008017.

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Activation-energy asymptotics is employed to explore effects of the Lewis number, the ratio of thermal to fuel diffusivity, in a one-dimensional model of steady motion of edges of reaction sheets. The propagation velocity of the edge is obtained as a function of the relevant Damköhler number, the ratio of the diffusion time to the chemical time. The results show how Lewis numbers different from unity can increase or decrease propagation velocities. Increasing the Lewis number increases the propagation velocity at large Damköhler numbers and decreases it at small Damköhler numbers. Advancing-edge and retreating-edge solutions are shown to exist simultaneously, at the same Damköhler number, if the Lewis number is sufficiently large. This multiplicity of solutions has a bearing on potential edge-flame configurations in non-uniform flows.

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Pitts, R. A. "Ion velocity distributions at the tokamak edge." Physics of Fluids B: Plasma Physics 3, no. 10 (October 1991): 2871–76. http://dx.doi.org/10.1063/1.859919.

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SHAN, H., B. MA, Z. ZHANG, and F. T. M. NIEUWSTADT. "Direct numerical simulation of a puff and a slug in transitional cylindrical pipe flow." Journal of Fluid Mechanics 387 (May 25, 1999): 39–60. http://dx.doi.org/10.1017/s0022112099004681.

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A direct numerical simulation of transitional pipe flow is carried out with the help of a spectral element method and used to investigate the localized regions of ‘turbulent’ flow that are observed in experiments. Two types of such regions can be distinguished: the puff and the slug. The puff, which is generally found at low values of the Reynolds numbers, is simulated for Re = 2200 where the Reynolds number Re is based on the mean velocity UB and pipe diameter D. The slug occurs at a higher Reynolds number and it is simulated for Re = 5000. The computations start with a laminar pipe flow to which is added a prescribed velocity disturbance at a given axial position and for a finite time. The disturbance then evolves further into a puff or slug structure.The simulations confirm the experimentally observed fact that for a puff the velocity near the leading edge changes more gradually than for a slug where an almost discontinuous change is observed. The positions of the leading and trailing edges of the puff and slug are computed from the simulations as a function of time. The propagation velocity of the leading edge is found to be constant and equal to 1.56UB and 1.69UB for the puff and slug, respectively. For the trailing edge the velocity is found to be 0.73UB and 0.52UB, respectively. By rescaling the simulation results obtained at various times to a fixed length, we define an ensemble average. This method is used to compute the average characteristics of the puff and slug such as the spatial distribution of the mean velocity, the turbulent velocity fluctuations and also the wall shear stress. By computing particle trajectories we have investigated the entrainment and detrainment of fluid by a puff and slug. We find that the puff detrains through its trailing edge and entrains through its leading edge. The slug entrains fluid through its leading and through most of its trailing edge. As a consequence the fluid inside the puff is constantly exchanged with fluid outside whereas the fluid inside a slug remains there. These entrainment/detrainment properties which are in agreement with the measurements of Wygnanski & Champagne (1973) imply that the puff has the characteristics of a wave phenomenon while the slug can be characterized more as a material property which travels with the flow.Finally, we have investigated in more detail the velocity field within the puff. In a coordinate system that travels with the mean velocity we find recirculation regions both near the trailing and leading edges which agrees at least qualitatively with experimental data. We also find streamwise vortices, predominantly in the trailing-edge region which have been also observed in experiments and which are believed to play an important role in the dynamics of the transition process.

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Sun, Keke, Ke Yang, Zhaoyu Ku, Yu Liu, and Huajun Dong. "Motion Velocity Detection of Circuit Breaker Operating Mechanism." Journal of Physics: Conference Series 2303, no. 1 (July 1, 2022): 012067. http://dx.doi.org/10.1088/1742-6596/2303/1/012067.

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Abstract The movement speed of the operating mechanism is one of the main factors affecting the breaking performance of the circuit breaker. To accurately detect the movement speed, this paper proposes an image processing method based on LabVIEW virtual instrument and designs a set of software and hardware systems for real-time movement speed detection of the operating mechanism. On the basis of the movement images of the operating mechanism collected by the high-speed camera, it uses the image processing module in LabVIEW to pre-process the images. The paper adopts the Laplacian edge detection operators to detect the edges and extract the edge feature information for straight line fitting and data processing. The experimental results show that the detection system can effectively detect the motion state of the operating mechanism, realize the real-time detection of the motion state of the operating mechanism, and provide technical support for the detection of the motion characteristics of the circuit breaker.

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Глухова, О. Е., А. П. Четвериков, and В. В. Шунаев. "Динамика локализованной кольцевой нелинейной волны в углеродной нанотрубке." Письма в журнал технической физики 47, no. 19 (2021): 15. http://dx.doi.org/10.21883/pjtf.2021.19.51506.18895.

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The propagation of nonlinear localized soliton-like super-acoustic longitudinal waves in a carbon nanotube was explored by the molecular dynamics modeling. Ring waves were excited by pulsed action on all the atoms of the edge zigzag layer and they got an initial velocity along the axis of the nanotube. It was shown that the velocity of a localized (soliton-like) ring super-acoustic wave increased with an increase in the initial velocity of the edge atoms. The calculated dependence of the propagating wave velocity on the initial velocity of the edge atoms was given.

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Wu, Jian, and Rong Di Han. "Experimental Investigation on Chip Deformation in Drilling 1Cr18Ni9Ti." Advanced Materials Research 426 (January 2012): 48–51. http://dx.doi.org/10.4028/www.scientific.net/amr.426.48.

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It is difficult to study the chip deformation due to the complexity of the chip formation process in drilling. The chip deformation has a direct effect on the drilling forces, drilling temperature and surface quality. The austenitic stainless steel 1Cr18Ni9Ti belongs to the hard-to-cut material, so it is necessary to investigate the chip deformation of 1Cr18Ni9Ti in drilling. An experimental investigation of the chip transformation process on the cutting edges using quick-stop of the drilling processes is carried out. Results indicate that the chip deformation increases with the increment of drilling velocity and decreases with the increment of the distance to chisel edge on cutting edge and the feed rate in drilling 1Cr18Ni9Ti; the chip deformation decreases with the increment of drilling velocity, and decreases with the increment of the distance to chisel edge on cutting edge and the feed rate in drilling AISI 1045; the chip deformation in drilling 1Cr18Ni9Ti is larger than that in drilling AISI 1045.

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Glukhova O. E., Chetverikov A. P., and Shunaev V. V. "Dynamics of a localized ring nonlinear wave in a carbon nanotube." Technical Physics Letters 48, no. 13 (2022): 37. http://dx.doi.org/10.21883/tpl.2022.13.53350.18895.

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The propagation of nonlinear localized soliton-like super-acoustic longitudinal waves in a carbon nanotube was explored by the molecular dynamics modeling. Ring waves were excited by pulsed action on all the atoms of the edge zigzag layer and they got an initial velocity along the axis of the nanotube. It was shown that the velocity of a localized (soliton-like) ring super-acoustic wave increased with an increase in the initial velocity of the edge atoms. The calculated dependence of the propagating wave velocity on the initial velocity of the edge atoms was given. Keywords: carbon nanotube, ring nonlinear waves, molecular dynamics.

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11

McCarthy, D. R. "Edge harmonic oscillations produced by toroidal velocity shear." Physics of Plasmas 9, no. 6 (June 2002): 2451–54. http://dx.doi.org/10.1063/1.1472503.

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12

Zhao, Peida, Matin Amani, Der-Hsien Lien, Geun Ho Ahn, Daisuke Kiriya, James P. Mastandrea, Joel W. Ager, Eli Yablonovitch, Daryl C. Chrzan, and Ali Javey. "Measuring the Edge Recombination Velocity of Monolayer Semiconductors." Nano Letters 17, no. 9 (August 18, 2017): 5356–60. http://dx.doi.org/10.1021/acs.nanolett.7b01770.

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13

Bex, P. "Deblurring of a drifting edge increases with velocity." Ophthalmic and Physiological Optics 14, no. 4 (October 1994): 437. http://dx.doi.org/10.1016/0275-5408(94)90182-1.

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14

Zhang, Hai Feng, Xiao Shu Zhang, Xiao Wei Liu, Yin Chun Liang, and Rui Weng. "Edge Effect on Viscous Drag of the Rotor in Liquid Floating Rotational Micro-Gyroscope." Key Engineering Materials 562-565 (July 2013): 286–91. http://dx.doi.org/10.4028/www.scientific.net/kem.562-565.286.

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A liquid floating rotational micro-gyroscope is proposed in this paper, whose stability is improved by liquid suspension. High rotor velocity is needed to improve its sensitivity. Edge effect is the phenomenon that sharp edges cause much more viscous drag. This work researches edge effect's influence on viscous drag to speed up the rotor. Flow field models of the sharp edge structure and fillet structure are established separately. Viscous drag is measured by simulation and experiment. Edge effect causes a lot of viscous drag and it can be reduced significantly by filleting the rotor. The maximal reduction is one third relative to the sharp edge structure, and it is reached when fillet curvature radius is half of rotor thickness.

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Park, Dae Woo, Grant H. Kruger, Jonathan M. Rubin, James Hamilton, Paul Gottschalk, Robert E. Dodde, Albert J. Shih, and William F. Weitzel. "Quantification of Ultrasound Correlation-Based Flow Velocity Mapping and Edge Velocity Gradient Measurement." Journal of Ultrasound in Medicine 32, no. 10 (October 2013): 1815–30. http://dx.doi.org/10.7863/ultra.32.10.1815.

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Simmons, P. J., and F. C. Rind. "Orthopteran DCMD neuron: a reevaluation of responses to moving objects. II. Critical cues for detecting approaching objects." Journal of Neurophysiology 68, no. 5 (November 1, 1992): 1667–82. http://dx.doi.org/10.1152/jn.1992.68.5.1667.

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1. We examine the critical image cues that are used by the locust visual system for the descending contralateral motion detector (DCMD) neuron to distinguish approaching from receding objects. Images were controlled by computer and presented on an electrostatic monitor. 2. Changes in overall luminance elicited much smaller and briefer responses from the DCMD than objects that appeared to approach the eye. Although a decrease in overall luminance might boost the response to an approaching dark object, movement of edges of the image is more important. 3. When two pairs of lines, in a cross-hairs configuration, were moved apart and then together again, the DCMD showed no preference for divergence compared with convergence of edges. A directional response was obtained by either making the lines increase in extent during divergence and decrease in extent during convergence; or by continually increasing the velocity of line movement during divergence and decreasing velocity during convergence. 4. The DCMD consistently gave a larger response to growing than to shrinking solid rectangular images. An increase compared with a decrease in the extent of edge in an image is, therefore, an important cue for the directionality of the response. For single moving edges of fixed extent, the neuron gave the largest response to edges that subtended 15 degrees at the eye. 5. The DCMD was very sensitive to the amount by which an edge traveled between frames on the display screen, with the largest responses generated by 2.5 degrees of travel. This implies that the neurons in the optic lobe that drive this movement-detecting system have receptive fields of about the same extent as a single ommatidium. 6. For edges moving up to 250 degree/s, the excitation of the DCMD increases with velocity. The response to an edge moving at a constant velocity adapts rapidly, in a manner that depends on velocity. Movement over one part of the retina can adapt the subsequent response to movement over another part of the retina. 7. For the DCMD to track and continue to respond to the image of an approaching object, the edges of the image must continually increase in velocity. This is the second important stimulus cue. 8. Edges of opposite contrasts (light-dark compared with dark-light) are processed in separate pathways that inhibit each other. This would contribute to the reduction of responses to wide-field movements.

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Mohammad Danil Arifin, Frengki Mohamad Felayati, and Andi Haris Muhammad. "Flow Separation Evaluation on Tubercle Ship Propeller." CFD Letters 14, no. 4 (May 6, 2022): 43–50. http://dx.doi.org/10.37934/cfdl.14.4.4350.

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Propeller design for ship propulsion is important based on efficiency and power output. Advanced propeller design has been proposed in recent research, such as the tubercle propeller. The modified propeller on the leading edge with a tubercle-like design has been improved. Moreover, some evaluation has been studied on the design and performance. In the present study, the tubercle design on the leading edge is evaluated, which focuses on the flow separation effect developed by the tubercle shape. A computational fluid dynamic (CFD) model is compared between the normal and tubercle leading edge. The flow total pressure, Reynold number velocity, and power surface acoustic are evaluated. The flow separation is generated in the leading edge due to the tubercle shape. Moreover, the tubercle shape reduces the total pressure at the propeller blade, especially at the edges. It also increases the Reynold number velocity at the surface due to the flow separation. However, the flow separation decreased the power acoustic surface, which means it lost some power on the propeller.

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Iwagami, Sho, Ryoya Tabata, Taizo Kobayashi, Yuji Hattori, and Kin’ya Takahashi. "Numerical study on edge tone with compressible direct numerical simulation: Sound intensity and jet motion." International Journal of Aeroacoustics 20, no. 3-4 (March 24, 2021): 283–316. http://dx.doi.org/10.1177/1475472x211003296.

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A two-dimensional model of the edge tone is studied by a highly accurate and reliable method of direct numerical simulation of the compressible Navier-Stokes equations, and used to verify key features observed in previous experimental and numerical studies, and to discover new features related to the jet motion and the edge tone generation mechanism. The first and second modes of the edge tone that are numerically reproduced agree well with Brown’s equation. In the mode transition region, dynamical mode transition is observed at a fixed jet velocity. For both first and second modes, the pressure distributions are antisymmetric with respect to the edge plate, and the sound intensity is proportional to the fifth power of the jet velocity. These results are consistent with the edge tone being radiated from a dipole-like source. Spatial profiles of the velocity and the velocity variance of the oscillating jet are also investigated for each mode over a range of the jet velocity including the mode transition regime. The amplitude of the velocity oscillation becomes constant with increasing jet velocity, while a measure of the amplitude of the velocity variance profile, which is introduced to characterize the strength of the jet fluctuation and named the ’fluctuation strength’, is proportional to the third power of the jet velocity. Some properties of the fluctuation strength correspond to properties of the sound intensity, including the first mode having larger amplitude than the second mode, and the way of deviating from the power law at smaller values of jet velocity and in the mode transition region. It is proposed that the third-power law exhibited by behavior of the fluctuation strength could be related to the increase of the skewness observed in the velocity profile with increase of jet velocity, and a model calculation is used to support this proposal.

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Xu, Wenjun, Longquan Liu, and Wu Xu. "Experiments and Finite Element Simulations of Composite Laminates Following Low Velocity On-Edge Impact Damage." Polymers 14, no. 9 (April 25, 2022): 1744. http://dx.doi.org/10.3390/polym14091744.

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Composites are widely used in aircraft structures that have free edges and are vulnerable to impact events during manufacturing and maintenance. On-edge impact may have a great contribution in terms of the compression strength loss of composites, but the influence remains unclear. This paper presents experiments and simulations of carbon-fiber-reinforced plastic (CFRP) materials with on-edge impact and compression after edge impact (CAEI). On-edge impact damage was introduced to the composite laminates through the drop weight method with 4, 6, 8 and 10 J impact energies, respectively. A special guide-rail-type fixture was used in the compression tests in which strain–force and load–displacement relationships were obtained. A continuous-step finite element model was proposed to simulate impact and compression. Continuum shell elements and Hashin failure criteria were used to simulate in-ply damage, and interlaminar damage was modelled by cohesive elements. The model was validated by correlating the experimental and numerical results. The investigation results revealed the relationships of the damage size and residual strength with the different impact energies. The crack length and delaminated area grow with the increase in impact energy. The residual compressive strength follows a downward trend with increasing impact energy.

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Xu, Wenjun, Longquan Liu, and Wu Xu. "Experiments and Finite Element Simulations of Composite Laminates Following Low Velocity On-Edge Impact Damage." Polymers 14, no. 9 (April 25, 2022): 1744. http://dx.doi.org/10.3390/polym14091744.

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Composites are widely used in aircraft structures that have free edges and are vulnerable to impact events during manufacturing and maintenance. On-edge impact may have a great contribution in terms of the compression strength loss of composites, but the influence remains unclear. This paper presents experiments and simulations of carbon-fiber-reinforced plastic (CFRP) materials with on-edge impact and compression after edge impact (CAEI). On-edge impact damage was introduced to the composite laminates through the drop weight method with 4, 6, 8 and 10 J impact energies, respectively. A special guide-rail-type fixture was used in the compression tests in which strain–force and load–displacement relationships were obtained. A continuous-step finite element model was proposed to simulate impact and compression. Continuum shell elements and Hashin failure criteria were used to simulate in-ply damage, and interlaminar damage was modelled by cohesive elements. The model was validated by correlating the experimental and numerical results. The investigation results revealed the relationships of the damage size and residual strength with the different impact energies. The crack length and delaminated area grow with the increase in impact energy. The residual compressive strength follows a downward trend with increasing impact energy.

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Xu, Wenjun, Longquan Liu, and Wu Xu. "Experiments and Finite Element Simulations of Composite Laminates Following Low Velocity On-Edge Impact Damage." Polymers 14, no. 9 (April 25, 2022): 1744. http://dx.doi.org/10.3390/polym14091744.

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Composites are widely used in aircraft structures that have free edges and are vulnerable to impact events during manufacturing and maintenance. On-edge impact may have a great contribution in terms of the compression strength loss of composites, but the influence remains unclear. This paper presents experiments and simulations of carbon-fiber-reinforced plastic (CFRP) materials with on-edge impact and compression after edge impact (CAEI). On-edge impact damage was introduced to the composite laminates through the drop weight method with 4, 6, 8 and 10 J impact energies, respectively. A special guide-rail-type fixture was used in the compression tests in which strain–force and load–displacement relationships were obtained. A continuous-step finite element model was proposed to simulate impact and compression. Continuum shell elements and Hashin failure criteria were used to simulate in-ply damage, and interlaminar damage was modelled by cohesive elements. The model was validated by correlating the experimental and numerical results. The investigation results revealed the relationships of the damage size and residual strength with the different impact energies. The crack length and delaminated area grow with the increase in impact energy. The residual compressive strength follows a downward trend with increasing impact energy.

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Prato, J., and B. Lakshminarayana. "Investigation of Compressor Rotor Wake Structure at Peak Pressure Rise Coefficient and Effects of Loading." Journal of Turbomachinery 115, no. 3 (July 1, 1993): 487–500. http://dx.doi.org/10.1115/1.2929279.

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This paper reports an experimental study of the three-dimensional characteristics of the mean velocity in the trailing-edge, near-wake, and far-wake regions of a highly loaded low-speed compressor rotor. The wake structure and decay characteristics are compared with the wake data in the same compressor with moderate loading. The experimental investigation was carried out using a rotating five-hole probe. The flow field was surveyed at various radial and axial locations downstream of the compressor rotor. Variations in the axial, tangential, and radial components of mean velocity at various axial and radial locations were derived from the data and compared with earlier data at lower loading to discern the effects of loading. It was found that the higher loading had the following effects: Higher total velocity defects were observed in the hub-wall region, increased wake growth rate in the tip region, faster decay of static pressure difference in the trailing-edge region, larger initial wake width in the trailing-edge region, increased rate of growth of the semi-wake width in the trailing-edge region, increased decay rate of radial velocity in the trailing-edge region, and decreased decay rate of the radial velocity in the far-wake region. Far wake properties were almost identical in both cases.

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Idehara, K., S. Tanaka, and N. Takeuchi. "High-velocity anomaly adjacent to the western edge of the Pacific low-velocity province." Geophysical Journal International 192, no. 1 (November 9, 2012): 1–6. http://dx.doi.org/10.1093/gji/ggs002.

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Zaccaria, M. A., and B. Lakshminarayana. "Unsteady Flow Field Due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part II—Rotor Exit Flow Field." Journal of Turbomachinery 119, no. 2 (April 1, 1997): 214–24. http://dx.doi.org/10.1115/1.2841104.

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The two-dimensional steady and unsteady flow field at midspan in a turbine rotor has been investigated experimentally using an LDV with an emphasis on the interaction of the nozzle wake with the rotor flow field. The velocity measurements are decomposed into a time-averaged velocity, a periodic velocity component, and an unresolved velocity component. The results in the rotor passage were presented in Part I. The flow field downstream of the rotor is presented in this paper. The rotor wake profiles and their decay characteristics were analyzed. Correlations are presented that match the decay of the various wake properties. The rotor wake velocity defect decays rapidly in the trailing edge region, becoming less rapid in the near and far wake regions. The rotor wake semi-wake width increases rapidly in the trailing edge region and then grows more gradually in the near and far wake regions. The decay of the maximum unresolved unsteadiness and maximum unresolved velocity cross correlations is very rapid in the trailing edge region and this trend slows in the far wake region. In the trailing edge region, the maximum periodic velocity correlations are much larger than the maximum unresolved velocity correlations. But the periodic velocity correlations decay much faster than the unresolved velocity correlations. The interactions of the nozzle and rotor wakes are also studied. While the interaction of the nozzle wake with the rotor wake does not influence the decay rate of the various wake properties, it does change the magnitude of the properties. These and other results are presented in this paper.

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CHAPMAN, C. J. "Energy paths in edge waves." Journal of Fluid Mechanics 426 (January 10, 2001): 135–54. http://dx.doi.org/10.1017/s0022112000002184.

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In this paper the energy streamlines, energy paths, and energy streak lines in a steady or unsteady inhomogeneous acoustic field next to an unstable oscillating boundary, such as a vortex sheet or shear layer, are determined. The theory in the paper applies also to an evanescent wave produced by total internal reflection, and to any other type of edge wave, e.g. a coastally or topographically trapped wave in geophysical fluid dynamics. The idea of the paper is that energy velocity, i.e. energy flux divided by energy density, is defined at every point in space and time, not merely when averaged over a cycle. Integration of the ordinary differential equation for energy velocity as a function of position and time gives the energy paths. These paths are calculated explicitly, and are found to have starting and finishing directions very different from those of cycle-averaged paths. The paper discusses the physical significance of averaged and non-averaged energy paths, especially in relation to causality. Many energy paths have cusps, at which the energy velocity is instantaneously zero. The domain of influence of an arbitrary point on the boundary of a steady acoustic edge wave is shown to lie within 45° of a certain direction, in agreement with a known result on shear-layer instability in compressible flow. The results are consistent with flow visualization photographs of near-field jet noise. The method of the paper determines domains of influence and causality in any wave problem with an explicit solution, for example as represented by a Fourier integral.

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Lee, C. K., C. L. Hsieh, J. C. Ruan, and C. Y. Wang. "Simulation of Meshing of Herringbone Double Circular-Arc Helical Gears using Multibody Dynamic Analysis Software." Journal of Physics: Conference Series 2287, no. 1 (June 1, 2022): 012023. http://dx.doi.org/10.1088/1742-6596/2287/1/012023.

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Abstract This paper aims to complete the simulation of meshing of a pair of herringbone double circular-arc helical gears by using the multibody dynamic analysis software, SolidWorks motion. Three types of edge modifications, including no edge modification, chamfered edge modification, and rounded edge modification, are applied respectively to the pair of gears. The output angular velocities and contact regions corresponding with the three types of edge modifications are analyzed. Moreover, whether the center distance assembly error affects the output angular velocity and contact regions are analyzed. The results obtained by the simulation of meshing show that rounded edge modification is better than chamfered edge modification, and chamfered edge modification is better than no edge modification. The center distance assembly error has no effect on the output angular velocity and has little effect on the contact regions. Therefore, double circular-arc helical gears are not sensitive to center distance assembly errors.

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McCarthy, D. R., J. F. Drake, and P. N. Guzdar. "Axisymmetric parallel velocity shear instability in the tokamak edge." Physics of Fluids B: Plasma Physics 5, no. 7 (July 1993): 2145–52. http://dx.doi.org/10.1063/1.860958.

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Cao, B., S. J. Zweben, D. P. Stotler, M. Bell, A. Diallo, S. M. Kaye, and B. LeBlanc. "Edge turbulence velocity changes with lithium coating on NSTX." Plasma Physics and Controlled Fusion 54, no. 11 (October 18, 2012): 112001. http://dx.doi.org/10.1088/0741-3335/54/11/112001.

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Coffey, C. S. "Velocity of moving edge dislocations in a crystalline solid." Physical Review B 34, no. 8 (October 15, 1986): 5674–77. http://dx.doi.org/10.1103/physrevb.34.5674.

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Neumeier, U. "Velocity and turbulence variations at the edge of saltmarshes." Continental Shelf Research 27, no. 8 (May 2007): 1046–59. http://dx.doi.org/10.1016/j.csr.2005.07.009.

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WASON, AMIT, WILLIAM F. CARNELL, and MICHAEL W. RENFRO*. "VELOCITY AND SCALAR MEASUREMENTS IN NEIGHBORING LIFTED EDGE FLAMES." Combustion Science and Technology 178, no. 5 (April 2006): 789–811. http://dx.doi.org/10.1080/00102200500271476.

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MUPPIDI, SUMAN, and KRISHNAN MAHESH. "Direct numerical simulation of round turbulent jets in crossflow." Journal of Fluid Mechanics 574 (February 15, 2007): 59–84. http://dx.doi.org/10.1017/s0022112006004034.

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Direct numerical simulation is used to study a round turbulent jet in a laminar crossflow. The ratio of bulk jet velocity to free-stream crossflow velocity is 5.7 and the Reynolds number based on the bulk jet velocity and the jet exit diameter is 5000. The mean velocity and turbulent intensities from the simulations are compared to data from the experiments by Su & Mungal (2004) and good agreement is observed. Additional quantities, not available from experiments, are presented. Turbulent kinetic energy budgets are computed for this flow. Examination of the budgets shows that the near field is far from a state of turbulent equilibrium – especially along the jet edges. Also – in the near field – peak kinetic energy production is observed close to the leading edge, while peak dissipation is observed toward the trailing edge of the jet. The results are used to comment upon the difficulty involved in predicting this flow using RANS computations. There exist regions in this flow where the pressure transport term, neglected by some models and poorly modelled by others, is significant. And past the jet exit, the flow is not close to established canonical flows on which most models appear to be based.

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33

FU, YU-XI, QUAN XIAO, HONG-FENG GAO, and SHU-RONG WANG. "Stimulus features eliciting visual responses from neurons in the nucleus lentiformis mesencephali in pigeons." Visual Neuroscience 15, no. 6 (November 1998): 1079–87. http://dx.doi.org/10.1017/s0952523898156055.

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The purpose of the present study was to find out what particular stimulus features, in addition to the direction and velocity of motion, specifically activate neurons in the nucleus lentiformis mesencephali (nLM) in pigeons. Visual responses of 60 nLM cells to a variety of computer-generated stimuli were extracellularly recorded and quantitatively analyzed. Ten recording sites were histologically verified to be localized within nLM with cobalt sulfide markings. It was shown that the pigeon nLM cells were specifically sensitive to the leading edge moving at the optimal velocity in the preferred direction through their excitatory receptive fields (ERFs). Generally speaking, nLM cells preferred black edges to white ones. However, this preference cannot be explained by OFF-responses to a light spot. The edge sharpness was also an essential factor influencing the responsive strength, with blurred edges producing little or no visual responses at all. These neurons vigorously responded to black edge orientated perpendicular to, and moved in, the preferred direction; the magnitude of visual responses was reduced with changing orientation. The spatial summation occurred in all neurons tested, characterized by the finding that neuronal firings increased as the leading edge was lengthened until saturation was reached. On the other hand, it appeared that nLM neurons could not detect any differences in the shape and area of stimuli with an identical edge. These data suggested that feature extraction characteristics of nLM neurons may be specialized for detecting optokinetic stimuli, but not for realizing pattern recognition. This seems to be at least one of the reasons why large-field gratings or random-dot patterns have been used to study visual responses of accessory optic neurons and optokinetic nystagmus, because many high-contrast edges in these stimuli can activate a neuron to periodically discharge, or groups of neurons to simultaneously fire to elicit optokinetic reflex.

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Zhuo, Liqiang, Huiru He, Ruimin Huang, Shaojian Su, Zhili Lin, Weibin Qiu, Beiju Huang, and Qiang Kan. "Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials." Nanomaterials 11, no. 7 (July 12, 2021): 1808. http://dx.doi.org/10.3390/nano11071808.

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The valley degree of freedom, like the spin degree of freedom in spintronics, is regarded as a new information carrier, promoting the emerging valley photonics. Although there exist topologically protected valley edge states which are immune to optical backscattering caused by defects and sharp edges at the inverse valley Hall phase interfaces composed of ordinary optical dielectric materials, the dispersion and the frequency range of the edge states cannot be tuned once the geometrical parameters of the materials are determined. In this paper, we propose a chirped valley graphene plasmonic metamaterial waveguide composed of the valley graphene plasmonic metamaterials (VGPMs) with regularly varying chemical potentials while keeping the geometrical parameters constant. Due to the excellent tunability of graphene, the proposed waveguide supports group velocity modulation and zero group velocity of the edge states, where the light field of different frequencies focuses at different specific locations. The proposed structures may find significant applications in the fields of slow light, micro–nano-optics, topological plasmonics, and on-chip light manipulation.

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Svensmark, Jacob, Steen H. Hansen, Davide Martizzi, Ben Moore, and Romaine Tessier. "Inferring the dark matter velocity anisotropy to the cluster edge." Monthly Notices of the Royal Astronomical Society 500, no. 3 (November 23, 2020): 3151–61. http://dx.doi.org/10.1093/mnras/staa3279.

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ABSTRACT Dark matter (DM) dominates the properties of large cosmological structures such as galaxy clusters, and the mass profiles of the DM have been inferred for these equilibrated structures for years by using cluster X-ray surface brightnesses and temperatures. A new method has been proposed, which should allow us to infer a dynamical property of the DM, namely the velocity anisotropy. For the gas, a similar velocity anisotropy is zero due to frequent collisions; however, the collisionless nature of DM allows it to be non-trivial. Numerical simulations have for years found non-zero and radially varying DM velocity anisotropies. Here we employ the method proposed by Hansen & Piffaretti, and developed by Høst et al. to infer the DM velocity anisotropy in the bright galaxy cluster Perseus, to near five times the radii previously obtained. We find the DM velocity anisotropy to be consistent with the results of numerical simulations, however, still with large error bars. At half the virial radius, we find the DM velocity anisotropy to be non-zero at 1.7$\, \sigma$, lending support to the collisionless nature of DM.

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Gursul, Ismet, and Donald Rockwell. "Vortex street impinging upon an elliptical leading edge." Journal of Fluid Mechanics 211 (February 1990): 211–42. http://dx.doi.org/10.1017/s0022112090001550.

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The interaction of a Kármán vortex street with an elliptical edge is investigated experimentally. Basic types of interaction, as a function of scale and transverse displacement of the incident vortex street, are revealed using flow visualization. Unsteady pressure fields induced by these interactions are measured by a phase-averaging technique and correlated with the visualized flow patterns for basic classes of interactions.For a generic vortex–edge interaction, measurements of the phase-averaged velocity field allow construction of streamlines and vorticity contours showing the details of the interaction, including distortion of the vortical structures near the edge. The pressure field is calculated from the measured velocity field and interpreted in relation to the vortical structures.Simulation of flow visualization using the measured velocity field demonstrates possible misinterpretations related to the underlying vorticity field.

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Debnath, Lokenath, and Pijush Pal Roy. "Propagation of edge waves in a thinly layered laminated medium with stress couples under initial stresses." Journal of Applied Mathematics and Simulation 1, no. 4 (January 1, 1988): 271–86. http://dx.doi.org/10.1155/s1048953388000206.

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The propagation of edge waves in a thinly layered laminated medium with stress couples under initial stresses is examined. Based upon an approximate representation of a laminated medium by an equivalent anisotropic continuum with average initial and couple stresses, an explicit form of frequency equation is obtained to derive the phase velocity of edge waves. Edge waves exist under certain conditions. The inclusion of couple stresses increases the velocity of wave propagation. For a specific compression, the presence of couple stresses increases the velocity of wave propagation with the increase of wave number, whereas the reverse is the case when there is no couple stress. Numerical computation is performed with graphical representations. Several special cases are also examined.

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Shen, Xue Fei, Tao Chen, and Ning Liu. "Patterning of ITO on Glass with Two-Step Using Excimer Laser and Wet Chemical Re-Etching." Advanced Materials Research 291-294 (July 2011): 1393–98. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.1393.

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ITO electrode patterns were fabricated using excimer laser direct-writing technique. The influence of the process parameters (the excimer laser fluence and the stage velocity) on the micromachining quality (the etching depth and ridge height of the edge ) of ITO patterns were experimentally studied. In this paper, the effect of laser fluence and the speed of working platform on the fabrication quality were discussed. The lower laser fluence and suitable platform speed will be very helpful to improve the edge quality of patterning of ITO. However, the recast ridge at the edge also was shown. Use of 39% solution of hydrochloric acid made it possible to further minimize the recast ridge at the edges.

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39

Zorya, I. V., G. M. Poletaev, and R. Yu Rakitin. "Energy and velocity of sliding of edge and screw dislocations in austenite and Hadfield steel: Molecular dynamics simulation." Izvestiya. Ferrous Metallurgy 65, no. 12 (December 31, 2022): 861–68. http://dx.doi.org/10.17073/0368-0797-2022-12-861-868.

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The sliding of edge and screw dislocations in Hadfield steel and in pure HCC iron (austenite) depending on temperature and deformation rate was studied by the method of molecular dynamics. The complete dislocation appears in the present model immediately in the form of a split into a pair of partial Shockley dislocations separated by a packing defect. The distance between partial dislocations is several nanometres. As the shear rate increases, this distance decreases. According to the data obtained, the energies of edge and screw dislocations in steel are higher than in pure austenite. The energy of the total edge dislocation in γ-iron and Hadfield steel averages 2.0 and 2.3 eV/Å, helical – 1.3 and 1.5 eV/Å respectively. Dependences of the sliding velocity of the edge and screw dislocations on the shear rate and temperature were obtained. The sliding velocity of the edge dislocation is in all cases higher than the screw one, which is explained by the difference in the propagation velocity of longitudinal and transverse waves in the material. With an increase in the shear rate, the sliding speed increases to a certain limit, depending on the propagation velocity of the corresponding elastic waves. At low and normal temperatures, the sliding velocity of dislocations in Hadfield steel is significantly (about one and a half times) lower compared to pure HCC iron. In pure iron, the sliding velocity of dislocations decreases with increasing temperature. However, for Hadfield steel, this dependence is nonmonotonic: as the temperature increases to about 500 K, the dislocation rate increases. That is probably due to the intensification of diffusion of impurity carbon atoms; then, as in iron, it decreases.

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Ajalli, Fariba, Mahmoud Mani, and Mozhgan Gharakhanlou. "Wake Frequency Analysis of a Plunging Airfoil with Trailing-Edge Strips." Applied Mechanics and Materials 225 (November 2012): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amm.225.3.

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Experimental measurements were conducted on a plunging Eppler 361 strip flapped airfoil to study wake structure in the wake. The heights of strip flap were 2.6% and 3.3% chord. The velocity in the wake was measured by hot-wire anemometry. It was found that the trailing-edge strip had different effects on the plunging wake profile during the oscillation cycle. At initial angle of 0 degree, the trailing-edge strip causes more velocity defect in the oscillation phases of 180º and 270º. At high initial angle 12 degrees, a significant decrease in value of velocity is found at 180º because of the leading edge vortex shedding. The power spectra of dominant frequencies were significantly increased by fitting the strip flap on the plunging airfoil.

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Schobeiri, T. "Optimum Trailing Edge Ejection for Cooled Gas Turbine Blades." Journal of Turbomachinery 111, no. 4 (October 1, 1989): 510–14. http://dx.doi.org/10.1115/1.3262301.

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The effect of trailing edge ejection on the flow downstream of a cooled gas turbine blade is investigated. Parameters that affect the mixing losses and therefore the efficiency of cooled blades are the ejection velocity ratio, the cooling mass flow ratio, the slot-width ratio, and the ejection angle. For ejection velocity ratio μ = 1, the trailing edge ejection reduces the mixing losses downstream to the cooled blade. For given cooling mass flow ratios, optimum slot-width/trailing edge ratios are found, which correspond to the minimum mixing loss coefficients.

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Gong, Liyuan, and Xiuling Wang. "Numerical Study of Noise Barriers’ Side Edge Effects on Pollutant Dispersion near Roadside under Various Thermal Stability Conditions." Fluids 3, no. 4 (December 8, 2018): 105. http://dx.doi.org/10.3390/fluids3040105.

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Roadside noise barrier helps to reduce downwind pollutant concentrations from vehicle emission. This positive characteristic of the construction feature can be explained by its interaction with flow distribution and species dispersion. In this paper, a three-dimensional numerical model has been developed to simulate highway pollutant dispersion—a realizable k-ε model was employed to model turbulent flow, and a non-reaction species dispersion model was applied to simulate species transport. First, numerical models were validated with experimental data, and good agreement was observed. Then, detailed simulations were conducted to study double barriers’ effects on highway pollutant dispersion under different settings: noise barriers with different heights, noise barriers with and without edge effects, and different atmospheric thermal boundary conditions. Results show that: (1) Noise barriers without edge effects cause bigger downwind velocity and turbulence intensity than noise barriers with edge effects. (2) At ground level, lower downwind pollutant concentration and higher pollutant concentration, near upwind barrier and between barriers, are observed for noise barriers without edge effect cases; higher on-road pollutant concentration can be seen near barrier side edges for cases with edge effect. (3) Downwind velocity and turbulence intensity increase as barrier height increases, which causes reduced downwind pollutant concentration. (4) With the same barrier height, under unstable atmospheric boundary condition, the lowest pollutant concentration can be found for both downwind and between barriers. Overall, these findings will provide valuable inputs to noise barrier design, so as to improve roadside neighborhood air quality.

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Rosado, M., R. F. Gabbasov, P. Repetto, I. Fuentes-Carrera, P. Amram, M. Martos, and O. Hernandez. "2D kinematics of the edge-on spiral galaxy ESO 379-006." Proceedings of the International Astronomical Union 8, S295 (August 2012): 234–35. http://dx.doi.org/10.1017/s1743921313004894.

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AbstractWe present a kinematical study of the marginally edge-on galaxy ESO 379-006. With Fabry-Perot spectroscopy at Hα we obtain velocity maps, the radial velocity field, and position-velocity diagrams parallel to the major and to the minor axis of the galaxy. We build the rotation curve of the galaxy and discuss the role of projection effects. The twisting of isovelocities in the radial velocity field of the disk of ESO 379-006 as well as a kinematical asymmetry found in the position-velocity diagrams parallel to the minor axis suggest the existence of non-circular motions that can be modeled by including a radial inflow besides the rotation motion. Extraplanar Diffuse Ionized gas was detected in this galaxy both from the images and from its kinematics. It is possible that the diffuse gas is lagging in rotation.

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Thoroddsen, S. T., M. J. Thoraval, K. Takehara, and T. G. Etoh. "Micro-bubble morphologies following drop impacts onto a pool surface." Journal of Fluid Mechanics 708 (August 14, 2012): 469–79. http://dx.doi.org/10.1017/jfm.2012.319.

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AbstractWhen a drop impacts at low velocity onto a pool surface, a hemispheric air layer cushions and can delay direct contact. Herein we use ultra-high-speed video to study the rupture of this layer, to explain the resulting variety of observed distribution of bubbles. The size and distribution of micro-bubbles is determined by the number and location of the primary punctures. Isolated holes lead to the formation of bubble necklaces when the edges of two growing holes meet, whereas bubble nets are produced by regular shedding of micro-bubbles from a sawtooth edge instability. For the most viscous liquids the air film contracts more rapidly than the capillary–viscous velocity through repeated spontaneous ruptures of the edge. From the speed of hole opening and the total volume of micro-bubbles we conclude that the air sheet ruptures when its thickness approaches ${\ensuremath{\sim} }100~\mathrm{nm} $.

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45

Banton, Tom, and Dennis M. Levi. "The Perceived Strength of Motion-Defined Edges." Perception 22, no. 10 (October 1993): 1195–204. http://dx.doi.org/10.1068/p221195.

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Performance on visual tasks involving the use of motion-defined contours is likely to depend on stimulus strength, but presently there are no empirical or experimental assessments of motion-defined contour strength. Therefore, a matching method was used to estimate the strength of suprathreshold motion-defined edges on a luminance-contrast scale. The perceived strength of a motion-defined contour was expressed as an equivalent luminance contrast; this allowed the use of a single scale which accommodates diverse motion-defined stimuli. Motion-defined edge strength estimated in this manner was an inverted U-shaped function of dot density and dot velocity, and spanned at least a fivefold range of edge strengths. For one observer, maximum motion-defined edge strength was equivalent to 79% luminance contrast, at least thirteen times the contrast detection threshold. The results are interpreted via a simple two-stage model for perceiving motion-defined edges.

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Buhl, Thomas, Mac Gaunaa, and Christian Bak. "Potential Load Reduction Using Airfoils with Variable Trailing Edge Geometry." Journal of Solar Energy Engineering 127, no. 4 (June 23, 2005): 503–16. http://dx.doi.org/10.1115/1.2037094.

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This paper presents an investigation of the potential for reduction of fluctuating loads on wind turbine blades with the use of flaplike deflectable trailing edges. More specifically, the aeroelastic response of an elastically mounted airfoil section with a deflectable trailing edge is investigated. This is done by coupling a model for the aerodynamic forces on a deforming airfoil with a linear spring/damper model for the elastic deformation of a rigid airfoil to which the forces associated with the deflection of the trailing edge are added. The analysis showed that when the airfoil experienced a wind step from 10to12m∕s the standard deviation of the normal force could be reduced by up to 85% when the flap was controlled by the reading of the airfoil flapwise position and velocity, while reductions of up to 95% could be obtained when the flap was controlled by the reading of the angle of attack. When the airfoil experienced a turbulent wind field, the standard deviation of the normal force could be reduced by 81% for control based on measured angle of attack. The maximum reduction using a combination of flapwise position and velocity was 75%. The maximum deflection of the trailing edge geometry was, in all the considered cases, small enough to justify the use of a potential flow code for calculation of the aerodynamic forces. Calculations showed that the effect of a time lag in the actuators and sensors may drastically reduce the efficiency of the control algorithm. Likewise, the effect of a low maximum actuation velocity reduces the efficiency of the control algorithm. The analysis of the two-dimensional (2D) aeroservoelastic system shown in this paper indicates that the potential of using trailing edge flaps for reduction of fluctuating loads is significant.

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Tosi, Fabio, Matteo Rocca, Filippo Aleotti, Matteo Poggi, Stefano Mattoccia, Flavia Tauro, Elena Toth, and Salvatore Grimaldi. "Enabling Image-Based Streamflow Monitoring at the Edge." Remote Sensing 12, no. 12 (June 25, 2020): 2047. http://dx.doi.org/10.3390/rs12122047.

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Monitoring streamflow velocity is of paramount importance for water resources management and in engineering practice. To this aim, image-based approaches have proved to be reliable systems to non-intrusively monitor water bodies in remote places at variable flow regimes. Nonetheless, to tackle their computational and energy requirements, offload processing and high-speed internet connections in the monitored environments, which are often difficult to access, is mandatory hence limiting the effective deployment of such techniques in several relevant circumstances. In this paper, we advance and simplify streamflow velocity monitoring by directly processing the image stream in situ with a low-power embedded system. By leveraging its standard parallel processing capability and exploiting functional simplifications, we achieve an accuracy comparable to state-of-the-art algorithms that typically require expensive computing devices and infrastructures. The advantage of monitoring streamflow velocity in situ with a lightweight and cost-effective embedded processing device is threefold. First, it circumvents the need for wideband internet connections, which are expensive and impractical in remote environments. Second, it massively reduces the overall energy consumption, bandwidth and deployment cost. Third, when monitoring more than one river section, processing “at the very edge” of the system efficiency improves scalability by a large margin, compared to offload solutions based on remote or cloud processing. Therefore, enabling streamflow velocity monitoring in situ with low-cost embedded devices would foster the widespread diffusion of gauge cameras even in developing countries where appropriate infrastructure might be not available or too expensive.

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Soranna, Francesco, Yi-Chih Chow, Oguz Uzol, and Joseph Katz. "The Effect of Inlet Guide Vanes Wake Impingement on the Flow Structure and Turbulence Around a Rotor Blade." Journal of Turbomachinery 128, no. 1 (February 1, 2005): 82–95. http://dx.doi.org/10.1115/1.2098755.

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The flow structure and turbulence around the leading and trailing edges of a rotor blade operating downstream of a row of inlet guide vanes (IGV) are investigated experimentally. Particle image velocimetry (PIV) measurements are performed in a refractive index matched facility that provides unobstructed view of the entire flow field. Data obtained at several rotor blade phases focus on modification to the flow structure and turbulence in the IGV wake as it propagates along the blade. The phase-averaged velocity distributions demonstrate that wake impingement significantly modifies the wall-parallel velocity component and its gradients along the blade. Due to spatially non-uniform velocity distribution, especially on the suction side, the wake deforms while propagating along the blade, expanding near the leading edge and shrinking near the trailing edge. While being exposed to the nonuniform strain field within the rotor passage, the turbulence within the IGV wake becomes spatially nonuniform and highly anisotropic. Several mechanisms, which are consistent with rapid distortion theory (RDT) and distribution of turbulence production rate, contribute to the observed trends. For example, streamwise (in rotor frame reference) diffusion in the aft part of the rotor passage enhances the streamwise fluctuations. Compression also enhances the turbulence production very near the leading edge. However, along the suction side, rapid changes to the direction of compression and extension cause negative production. The so-called wall blockage effect reduces the wall-normal component.

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Guillet, Thibault, Martin Coux, David Quéré, and Christophe Clanet. "Path instabilities of streamlined bodies." Journal of Fluid Mechanics 864 (February 7, 2019): 286–302. http://dx.doi.org/10.1017/jfm.2018.1031.

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We study the trajectory and the maximum diving depth of floating axisymmetric streamlined bodies impacting water with a vertical velocity. Three different types of underwater trajectory can be observed. For a centre of mass of the projectile located close to its leading edge, the trajectory is either straight at low velocity or y-shaped at high velocity. When the centre of mass is far from the leading edge, the trajectory has a U-shape, independent of the initial velocity. We first characterize experimentally the aerodynamic properties of the projectile and then solve the equations of motion to recover the three types of trajectories. We finally discuss the transitions between the different regimes.

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Zweben, S. J., A. Diallo, M. Lampert, T. Stoltzfus-Dueck, and S. Banerjee. "Edge turbulence velocity preceding the L-H transition in NSTX." Physics of Plasmas 28, no. 3 (March 2021): 032304. http://dx.doi.org/10.1063/5.0039153.

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Journal articles on the topic 'Edge velocity'

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