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Journal articles on the topic 'Rankin Vortex'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

KONDOU, Shuuji, Hiroshi YAMASHITA, Masahisa SHINODA, and Kazuhiro YAMAMOTO. "A Numerical Study on Effect of Vortex Core Radius on Premixed Flame Propagation in Rankin Vortex Flow." Transactions of the Japan Society of Mechanical Engineers Series B 74, no. 747 (2008): 2387–92. http://dx.doi.org/10.1299/kikaib.74.2387.

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2

Wood, Vincent T., and Luther W. White. "A Parametric Wind–Pressure Relationship for Rankine versus Non-Rankine Cyclostrophic Vortices." Journal of Atmospheric and Oceanic Technology 30, no. 12 (2013): 2850–67. http://dx.doi.org/10.1175/jtech-d-13-00041.1.

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Abstract A parametric tangential wind profile model is presented for depicting representative pressure deficit profiles corresponding to varying tangential wind profiles of a cyclostrophic, axisymmetric vortex. The model employs five key parameters per wind profile: tangential velocity maximum, radius of the maximum, and three shape parameters that control different portions of the profile. The model coupled with the cyclostrophic balance assumption offers a diagnostic tool for estimating and examining a radial profile of pressure deficit deduced from a theoretical superimposing tangential win

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3

GORSHKOV, KONSTANTIN A., LEV A. OSTROVSKY, and IRINA A. SOUSTOVA. "Perturbation theory for Rankine vortices." Journal of Fluid Mechanics 404 (February 10, 2000): 1–25. http://dx.doi.org/10.1017/s0022112099007211.

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A perturbation scheme is constructed to describe the evolution of stable, localized Rankine-type hydrodynamic vortices under the action of disturbances such as density stratification. It is based on the elimination of singularities in perturbations by using the necessary orthogonality conditions which determine the vortex motion. Along with the discrete-spectrum modes of the linearized problem which can be kept finite by imposing the orthogonality conditions, the continuous-spectrum perturbations play a crucial role. It is shown that in a stratified fluid, a single (monopole) vortex can be des

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4

Kuo, Hung-Chi, Wayne H. Schubert, Chia-Ling Tsai, and Yu-Fen Kuo. "Vortex Interactions and Barotropic Aspects of Concentric Eyewall Formation." Monthly Weather Review 136, no. 12 (2008): 5183–98. http://dx.doi.org/10.1175/2008mwr2378.1.

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Abstract Concentric eyewall formation can be idealized as the interaction of a tropical cyclone core with nearby weaker vorticity of various spatial scales. This paper considers barotropic aspects of concentric eyewall formation from modified Rankine vortices. In this framework, the following parameters are found to be important in concentric eyewall formation: vorticity strength ratio, separation distance, companion vortex size, and core vortex skirt parameter. A vorticity skirt on the core vortex affects the filamentation dynamics in two important ways. First, the vorticity skirt lengthens t

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5

Roy, Anubhab, and Ganesh Subramanian. "Linearized oscillations of a vortex column: the singular eigenfunctions." Journal of Fluid Mechanics 741 (February 20, 2014): 404–60. http://dx.doi.org/10.1017/jfm.2013.666.

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AbstractIn 1880 Lord Kelvin analysed the linearized inviscid oscillations of a Rankine vortex as part of a theory of vortex atoms. These eponymously named neutrally stable modes are, however, exceptional regular oscillations that make up the discrete spectrum of the Rankine vortex. In this paper, we examine the singular oscillations that make up the continuous spectrum (CS) and span the entire base state range of frequencies. In two dimensions, the CS eigenfunctions have a twin-vortex-sheet structure similar to that known from earlier investigations of parallel flows with piecewise linear velo

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6

Jayavel, S., Pratish P. Patil, and Shaligram Tiwari. "Interaction of a skewed Rankine vortex pair." Physics of Fluids 20, no. 8 (2008): 083601. http://dx.doi.org/10.1063/1.2969115.

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7

Wang, Lifeng, Ruifeng Hu, Jun Zhang, and Yunpeng Ma. "On the Vortex Detection Method Using Continuous Wavelet Transform with Application to Propeller Wake Analysis." Mathematical Problems in Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/242917.

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The method based on the continuous wavelet transformation to detect and characterize two-dimensional vortex is analyzed for a synthetic flow and applied to vortex detection of propeller wake. The characteristics of a vortex, such as center location, core radius, and circulation, are extracted based on the Lamb-Oseen and Rankine vortex models, the latter of which is a novel attempt. The effects of various factors such as the difference scheme, the grid and scale discretization, transform variable, and vortex model on vortex detection have been investigated thoroughly. The method is further appl

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8

Gorecki, Piotr, and Rathinam Panneer Selvam. "Rankine combined vortex interaction with a rectangular prism." International Journal of Computational Fluid Dynamics 29, no. 1 (2015): 120–32. http://dx.doi.org/10.1080/10618562.2015.1010524.

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9

Ali, Md Shahjahan, Takashi Hosoda, and Ichiro Kimura. "Unsteady RANS and LES Simulation of an Ideal Rankine Vortex Decay." Advances in Civil Engineering 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/523839.

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The 3D numerical simulation was carried out for an idealized Rankine vortex using nonlineark-εmodel (one kind of RANS model) and large eddy simulation (LES) techniques. In this 3D simulation, the vortex flow field was given to rotate with the vertical axis in a free surface rectangular domain. In order to investigate the predictability of standard (linear) and non-lineark-εmodels, the decay of a trailing vortex was simulated and compared with previous DNS data. The governing equations for mean velocities and turbulent flows were discretized with the finite volume method based on a staggered gr

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10

Zhou, Kai, and Chao Zhou. "Effects of upstream Rankine vortex on tip leakage vortex breakdown in a subsonic turbine." Aerospace Science and Technology 99 (April 2020): 105776. http://dx.doi.org/10.1016/j.ast.2020.105776.

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11

Hao, Zong Rui, Juan Xu, Hai Yan Bie, and Zhong Hai Zhou. "Numerical Simulation of Three-Dimensional Unsteady Flow Field in the Cyclone." Advanced Materials Research 774-776 (September 2013): 258–61. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.258.

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Large eddy simulation to describe the turbulent flow of airflow field was used to calculate the unsteady turbulent flow characteristics in the cyclone. It funded that the tangential velocity in the cyclone profile behaved like rankine vortex, with the downward semi-free vortex of the outer layer and the upward forced vortex. With the increasing import gas velocity, the swirling strength of the center increased which reduced collection efficiency by clouding the dust particles in the ash bucket to the center airflow.

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12

Riccardi, G., and D. Durante. "Velocity Induced by a Plane Uniform Vortex Having the Schwarz Function of Its Boundary with Two Simple Poles." Journal of Applied Mathematics 2008 (2008): 1–40. http://dx.doi.org/10.1155/2008/586567.

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The velocity induced by a plane, uniform vortex is investigated through the use of an integral relation between Schwarz function of the vortex boundary and conjugate of the velocity. The analysis is restricted to a certain class of vortices, the boundaries of which are described through conformal maps onto the unit circle and the corresponding Schwarz functions possess two poles in the plane of the circle. The dependence of the velocity field on the vortex shape is investigated by comparing velocity and streamfunction with the ones of the equivalent Rankine vortex (which has the same vorticity

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13

Gonzalez, R., and C. D. Vigh. "Study of a Rankine vortex with axial velocity discontinuity in an infinite." Anales AFA 27, no. 4 (2017): 121–26. http://dx.doi.org/10.31527/analesafa.2016.27.4.121.

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14

XIE, HuYue, Yun CAO, FengHua QIN, and XiSheng LUO. "The slip effect of micro-droplets in Rankine vortex." SCIENTIA SINICA Physica, Mechanica & Astronomica 47, no. 12 (2017): 124702. http://dx.doi.org/10.1360/sspma2017-00075.

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15

Lacaze, Laurent, Anne-Laure Birbaud, and Stéphane Le Dizès. "Elliptic instability in a Rankine vortex with axial flow." Physics of Fluids 17, no. 1 (2005): 017101–017101. http://dx.doi.org/10.1063/1.1814987.

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16

Khoo, B. C., K. S. Yeo, and D. F. Lim. "The axisymmetric boundary layer beneath a Rankine-like vortex." Experiments in Fluids 22, no. 4 (1997): 300–311. http://dx.doi.org/10.1007/s003480050052.

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17

Mian, Lin, Li Jiachun, and Li Li. "Simulation of typhoon's anomalous track (I)—Rankine vortex model." Applied Mathematics and Mechanics 19, no. 3 (1998): 207–11. http://dx.doi.org/10.1007/bf02453384.

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18

Ligneul, P., and R. Latorre. "Study of Nuclei Distribution and Vortex Diffusion Influence on Nuclei Capture by a Tip Vortex and Nuclei Capture Noise." Journal of Fluids Engineering 115, no. 3 (1993): 504–7. http://dx.doi.org/10.1115/1.2910167.

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Earlier studies of cavitation nuclei behavior in the presence of a Rankine tip vortex have shown that the nuclei is attracted or captured by the vortex pressure field and during this process noise is produced by the rapid nuclei growth. The present paper extends the study of Ligneul and Latorre (1989). The capture of nuclei by the tip vortex was characterized by an index M which depends on the nuclei radius, initial location, and the vortex circulation. To clarify the nuclei distribution effected by this capture process, the frequency of nuclei capture is derived in terms of the nuclei distrib

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19

Aboelkassem, Yasser, Georgios H. Vatistas, and Nabil Esmail. "Viscous dissipation of Rankine vortex profile in zero meridional flow." Acta Mechanica Sinica 21, no. 6 (2005): 550–56. http://dx.doi.org/10.1007/s10409-005-0073-3.

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20

Zavershinskii, I. P., A. I. Klimov, N. E. Molevich, and D. P. Porfir’ev. "Rankine vortex evolution in a gas with heat release source." Technical Physics Letters 35, no. 4 (2009): 344–45. http://dx.doi.org/10.1134/s1063785009040166.

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21

Eloy, Christophe, and Stéphane Le Dizès. "Stability of the Rankine vortex in a multipolar strain field." Physics of Fluids 13, no. 3 (2001): 660–76. http://dx.doi.org/10.1063/1.1345716.

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22

Doronina, O. A., P. A. Bakhvalov, and T. K. Kozubskaya. "Numerical study of acoustic radiation dynamics of a Rankine vortex." Acoustical Physics 62, no. 4 (2016): 467–77. http://dx.doi.org/10.1134/s1063771016040060.

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23

Lazar, Ayah, A. Stegner, and E. Heifetz. "Inertial instability of intense stratified anticyclones. Part 1. Generalized stability criterion." Journal of Fluid Mechanics 732 (September 6, 2013): 457–84. http://dx.doi.org/10.1017/jfm.2013.412.

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AbstractThe stability of axisymmetric vortices to inertial perturbations is investigated by means of linear stability analysis, taking into account stratification, vertical eddy viscosity, as well as finite depth of the flow. We consider different types of circular barotropic vortices in a linearly stratified shallow layer confined with rigid lids. For the simplest case of the Rankine vortex we develop an asymptotic analytic dispersion relation and a marginal stability criterion, which compares well with numerical results. This is a further generalization to the well-known generalized Rayleigh

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24

Burow, Daniel, Hannah V. Herrero, and Kelsey N. Ellis. "Damage Analysis of Three Long-Track Tornadoes Using High-Resolution Satellite Imagery." Atmosphere 11, no. 6 (2020): 613. http://dx.doi.org/10.3390/atmos11060613.

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Remote sensing of tornado damage can provide valuable observations for post-event surveys and reconstructions. The tornadoes of 3 March 2019 in the southeastern United States are an ideal opportunity to relate high-resolution satellite imagery of damage with estimated wind speeds from post-event surveys, as well as with the Rankine vortex tornado wind field model. Of the spectral metrics tested, the strongest correlations with survey-estimated wind speeds are found using a Normalized Difference Vegetation Index (NDVI, used as a proxy for vegetation health) difference image and a principal comp

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25

Zhao, Bowen, Emma Chieusse-Gérard, and Glenn Flierl. "Influence of Bottom Topography on Vortex Stability." Journal of Physical Oceanography 49, no. 12 (2019): 3199–219. http://dx.doi.org/10.1175/jpo-d-19-0049.1.

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AbstractThe effects of topography on the linear stability of both barotropic vortices and two-layer, baroclinic vortices are examined by considering cylindrical topography and vortices with stepwise relative vorticity profiles in the quasigeostrophic approximation. Four vortex configurations are considered, classified by the number of relative vorticity steps in the horizontal and the number of layers in the vertical: barotropic one-step vortex (Rankine vortex), barotropic two-step vortex, and their two-layer, baroclinic counterparts with the vorticity steps in the upper layer. In the barotrop

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26

Toninelli, Ermes, Reuben S. Aspden, David Phillips, Graham M. Gibson, and Miles J. Padgett. "The transition from a coherent optical vortex to a Rankine vortex: beam contrast dependence on topological charge." Journal of Modern Optics 63, sup3 (2016): S51—S56. http://dx.doi.org/10.1080/09500340.2016.1234651.

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27

BALMFORTH, N. J., STEFAN G. LLEWELLYN SMITH, and W. R. YOUNG. "Disturbing vortices." Journal of Fluid Mechanics 426 (January 10, 2001): 95–133. http://dx.doi.org/10.1017/s0022112000002159.

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Inviscid spatially compact vortices (such as the Rankine vortex) have discrete Kelvin modes. For these modes, the critical radius, at which the rotation frequency of the wave matches the angular velocity of the fluid, lies outside the vortex core. When such a vortex is not perfectly compact, but has a weak vorticity distribution beyond the core, these Kelvin disturbances are singular at the critical radius and become ‘quasi-modes’. These are not true eigenmodes but have streamfunction perturbations that decay exponentially with time while the associated vorticity wraps up into a tight spiral w

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28

Chang, Pao-Liang, Wei-Ting Fang, Pin-Fang Lin, and Ming-Jen Yang. "A Vortex-Based Doppler Velocity Dealiasing Algorithm for Tropical Cyclones." Journal of Atmospheric and Oceanic Technology 36, no. 8 (2019): 1521–45. http://dx.doi.org/10.1175/jtech-d-18-0139.1.

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AbstractIn this study, a vortex-based Doppler velocity dealiasing (VDVD) algorithm for tropical cyclones (TCs) is proposed. The algorithm uses a Rankine combined vortex model as a reference field for dealiasing based on an inner–outer iterative procedure. The structure of the reference vortex is adjusted in an inner iterative procedure of VDVD that applies the ground-based velocity track display (GBVTD) technique. The outer loop of the VDVD based on the GBVTD-simplex algorithm is used for center correction. The VDVD is able to recover not only the aliased Doppler velocities from a simulated sy

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29

Prabhu, M., R. Ajith Kumar, T. H. Gopikrishnan, et al. "Rankine Vortex Formation during Draining: A New Twin Port Suppression Strategy." Journal of Applied Fluid Mechanics 13, no. 1 (2020): 147–60. http://dx.doi.org/10.29252/jafm.13.01.30202.

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30

Blanco-Rodríguez, Francisco J., and Stéphane Le Dizès. "Curvature instability of a curved Batchelor vortex." Journal of Fluid Mechanics 814 (February 6, 2017): 397–415. http://dx.doi.org/10.1017/jfm.2017.34.

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In this paper, we analyse the curvature instability of a curved Batchelor vortex. We consider this short-wavelength instability when the radius of curvature of the vortex centreline is large compared with the vortex core size. In this limit, the curvature instability can be interpreted as a resonant phenomenon. It results from the resonant coupling of two Kelvin modes of the underlying Batchelor vortex with the dipolar correction induced by curvature. The condition of resonance of the two modes is analysed in detail as a function of the axial jet strength of the Batchelor vortex. In contrast t

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31

Wood, Vincent T., and Rodger A. Brown. "Simulated Tornadic Vortex Signatures of Tornado-Like Vortices Having One- and Two-Celled Structures." Journal of Applied Meteorology and Climatology 50, no. 11 (2011): 2338–42. http://dx.doi.org/10.1175/jamc-d-11-0118.1.

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AbstractA tornadic vortex signature (TVS) is a degraded Doppler velocity signature that occurs when the tangential velocity core region of a tornado is smaller than the effective beamwidth of a sampling Doppler radar. Early Doppler radar simulations, which used a uniform reflectivity distribution across an idealized Rankine vortex, showed that the extreme Doppler velocity peaks of a TVS profile are separated by approximately one beamwidth. The simulations also indicated that neither the size nor the strength of the tornado is recoverable from a TVS. The current study was undertaken to investig

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32

Abrahamson, S., and S. Lonnes. "An Integral Method for Turbulent Boundary Layers on Rotating Disks." Journal of Fluids Engineering 115, no. 4 (1993): 614–19. http://dx.doi.org/10.1115/1.2910188.

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An integral method for computing turbulent boundary layers on rotating disks has been developed using a power law profile for the tangential velocity and a new model for the radial profile. A similarity solution results from the formulation. Radial transport, boundary layer growth, and drag on the disk were computed for the case of a forced vortex frees tream flow. The results were compared to previous similarity solutions. The method was extended to a Rankine vortex freestream flow. Differential equations for boundary layer parameters were developed and solved for different Reynolds numbers t

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33

Tavares Dias do Rio Vaz, Déborah Aline, Jerson Rogério Pinheiro Vaz, André Luiz Amarante Mesquita, João Tavares Pinho, and Antonio Cesar Pinho Brasil Junior. "Optimum aerodynamic design for wind turbine blade with a Rankine vortex wake." Renewable Energy 55 (July 2013): 296–304. http://dx.doi.org/10.1016/j.renene.2012.12.027.

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34

Wang, Xiaokun, Sinuo Liu, Xiaojuan Ban, Yanrui Xu, Jing Zhou, and Jiří Kosinka. "Robust turbulence simulation for particle-based fluids using the Rankine vortex model." Visual Computer 36, no. 10-12 (2020): 2285–98. http://dx.doi.org/10.1007/s00371-020-01914-5.

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35

Lasheras, Juan C., and Kek-Kiong Tio. "Dynamics of a Small Spherical Particle in Steady Two-Dimensional Vortex Flows." Applied Mechanics Reviews 47, no. 6S (1994): S61—S69. http://dx.doi.org/10.1115/1.3124442.

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The equation of motion of a small spherical particle in an isolated Rankine vortex is analyzed using an asymptotic scheme valid for the limiting case of small Stokes number St. The effects of particle inertia and added mass, gravity, the acceleration of the fluid, viscous drag, and the Basset history force are taken into consideration. For the case of an isolated Rankine vortex, the analysis shows that in the region where the fluid velocity is large enough, the viscous drag constrains the particle to move with a velocity equal to that of the fluid plus a perturbation of order St. This perturba

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36

Maicke, Brian A., and Joseph Majdalani. "A constant shear stress core flow model of the bidirectional vortex." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, no. 2103 (2008): 915–35. http://dx.doi.org/10.1098/rspa.2008.0342.

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In this paper, we discuss the merits of two models for the swirl velocity in the core of a confined bidirectional vortex. The first is piecewise, Rankine-like, based on a combined-vortex representation. It stems from the notion that a uniform shear stress distribution may be assumed in the inner vortex region of a cyclone, especially at high Reynolds numbers. Thereafter, direct integration of the shear stress enables us to retrieve an expression for the swirl velocity that overcomes the inviscid singularity at the centreline. The second model consists of a modified asymptotic solution to the p

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37

Park, Junho, and Paul Billant. "Radiative instability of an anticyclonic vortex in a stratified rotating fluid." Journal of Fluid Mechanics 707 (July 27, 2012): 381–92. http://dx.doi.org/10.1017/jfm.2012.286.

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AbstractIn strongly stratified fluids, an axisymmetric vertical columnar vortex is unstable because of a spontaneous radiation of internal waves. The growth rate of this radiative instability is strongly reduced in the presence of a cyclonic background rotation $f/ 2$ and is smaller than the growth rate of the centrifugal instability for anticyclonic rotation, so it is generally expected to affect vortices in geophysical flows only if the Rossby number $Ro= 2\Omega / f$ is large (where $\Omega $ is the angular velocity of the vortex). However, we show here that an anticyclonic Rankine vortex w

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38

Szantyr, Jan. "Dynamic interaction of the cavitating propeller tip vortex with the rudder." Polish Maritime Research 14, no. 4 (2007): 10–14. http://dx.doi.org/10.2478/v10012-007-0033-x.

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Dynamic interaction of the cavitating propeller tip vortex with the rudder The hydrodynamic interaction between the ship propeller and the rudder has many aspects. One of the most interesting is the interaction between the cavitating tip vortex shed from the propeller blades and the rudder. This interaction leads to strongly dynamic behaviour of the cavitating vortex, which in turn generates unusually high pressure pulses in its vicinity. Possibly accurate prediction of these pulses is one of the most important problems in the hydrodynamic design of a new ship. The paper presents a relatively

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39

OKULOV, V. L., and J. N. SØRENSEN. "Stability of helical tip vortices in a rotor far wake." Journal of Fluid Mechanics 576 (March 28, 2007): 1–25. http://dx.doi.org/10.1017/s0022112006004228.

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As a means of analysing the stability of the wake behind a multi-bladed rotor the stability of a multiplicity of helical vortices embedded in an assigned flow field is addressed. In the model the tip vortices in the far wake are approximated by infinitely long helical vortices with constant pitch and radius. The work is a further development of a model developed in Okulov (J. Fluid Mech., vol. 521, p. 319) in which the linear stability of N equally azimuthally spaced helical vortices was considered. In the present work the analysis is extended to include an assigned vorticity field due to root

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40

Quaranta, Hugo Umberto, Hadrien Bolnot, and Thomas Leweke. "Long-wave instability of a helical vortex." Journal of Fluid Mechanics 780 (September 9, 2015): 687–716. http://dx.doi.org/10.1017/jfm.2015.479.

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We investigate the instability of a single helical vortex filament of small pitch with respect to displacement perturbations whose wavelength is large compared to the vortex core size. We first revisit previous theoretical analyses concerning infinite Rankine vortices, and consider in addition the more realistic case of vortices with Gausssian vorticity distributions and axial core flow. We show that the various instability modes are related to the local pairing of successive helix turns through mutual induction, and that the growth rate curve can be qualitatively and quantitatively predicted

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41

Francis, J., and D. Parker. "Numerical simulation of observed flow phenomena in the supply and control ports and associated feed channels of a mini-vortex amplifier." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 5 (2015): 756–81. http://dx.doi.org/10.1177/0954406215573599.

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The trajectory and reach of jets issuing from tangential control ports at the periphery of a vortex amplifier's swirl chamber depend largely on design geometry, size and pressures applied. Excessive control port pressure causes these jets to extend too far across the face of the radial supply ports, to impact on the opposing supply port wall whereupon, they bifurcate to create back diffusion of control port flow along the supply port channels. Flow through vortex amplifier geometry is simulated using a baseline Reynolds stress turbulence model with Computational Fluid Dynamics (CFX) automatic

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42

Perrot, Xavier, and Xavier Carton. "Instability of a two-step Rankine vortex in a reduced gravity QG model." Fluid Dynamics Research 46, no. 3 (2014): 031417. http://dx.doi.org/10.1088/0169-5983/46/3/031417.

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43

Gonzalez, Israel, Amaryllis Cotto, and Hugh E. Willoughby. "Synthesis of Vortex Rossby Waves. Part II: Vortex Motion and Waves in the Outer Waveguide." Journal of the Atmospheric Sciences 72, no. 10 (2015): 3958–74. http://dx.doi.org/10.1175/jas-d-15-0005.1.

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Abstract Beta, the meridional gradient of planetary vorticity, causes tropical cyclones to propagate poleward and westward at approximately 2 m s−1. In a previous shallow-water linear model, the simulated vortex accelerated without limit, ostensibly because beta forced a free linear mode. In the analogous nonlinear model, wave–wave interaction limited the propagation speed. Subsequent work based upon the asymmetric balance (AB) approximation was unable to replicate the linear result. The present barotropic nondivergent model replicates the linear beta gyres as a streamfunction dipole with a un

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44

Holland, Andrew P., Allen J. Riordan, and E. C. Franklin. "A Simple Model for Simulating Tornado Damage in Forests." Journal of Applied Meteorology and Climatology 45, no. 12 (2006): 1597–611. http://dx.doi.org/10.1175/jam2413.1.

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Abstract An analytical model is presented to describe patterns of downed trees produced by tornadic winds. The model uses a combined Rankine vortex of specified tangential and radial components to describe a simple tornado circulation. A total wind field is then computed by adding the forward motion of the vortex. The lateral and vertical forces on modeled tree stands are then computed and are compared with physical characteristics of Scots and loblolly pine. From this model, patterns of windfall are computed and are compared to reveal three basic damage patterns: cross-track symmetric, along-

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45

PRADEEP, D. S., and F. HUSSAIN. "Core dynamics of a strained vortex: instability and transition." Journal of Fluid Mechanics 447 (October 30, 2001): 247–85. http://dx.doi.org/10.1017/s0022112001005869.

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We study the instability of a laminar vortex column (in an external orthogonal strain field) to an axisymmetric core size perturbation, and the resulting transition to fine-scale turbulence. The perturbation, which evolves as a standing wave oscillation (i.e. core dynamics, CD), is inviscidly amplified by the external strain. Analysis of a weakly strained Rankine vortex explains the physical mechanism of instability: resonant interaction between the perturbation – the azimuthal wavenumber m = 0 wave – and m = ±2 waves. The CD instability (CDI) – a type of elliptic instability – experiences the

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46

Potvin, Corey K., Alan Shapiro, Michael I. Biggerstaff, and Joshua M. Wurman. "The VDAC Technique: A Variational Method for Detecting and Characterizing Convective Vortices in Multiple-Doppler Radar Data." Monthly Weather Review 139, no. 8 (2011): 2593–613. http://dx.doi.org/10.1175/2011mwr3638.1.

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AbstractThe vortex detection and characterization (VDAC) technique is designed to identify tornadoes, mesocyclones, and other convective vortices in multiple-Doppler radar data and retrieve their size, strength, and translational velocity. The technique consists of fitting radial wind data from two or more radars to a simple analytical model of a vortex and its near environment. The model combines a uniform flow, linear shear flow, linear divergence flow (all of which comprise a broad-scale flow), and modified combined Rankine vortex. The vortex and its environmental flow are allowed to transl

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Brown, Rodger A., and Vincent T. Wood. "The Tornadic Vortex Signature: An Update." Weather and Forecasting 27, no. 2 (2012): 525–30. http://dx.doi.org/10.1175/waf-d-11-00111.1.

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Abstract A tornadic vortex signature (TVS) is a degraded Doppler velocity signature of a tornado that occurs when the core region of a tornado is smaller than the half-power beamwidth of the sampling Doppler radar. Soon after the TVS was discovered in the mid-1970s, simulations were conducted to verify that the signature did indeed represent a tornado. The simulations, which used a uniform reflectivity distribution across a Rankine vortex model, indicated that the extreme positive and negative Doppler velocity values of the signature should be separated by about one half-power beamwidth regard

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Davies-Jones, Robert P., and Vincent T. Wood. "Simulated Doppler Velocity Signatures of Evolving Tornado-Like Vortices." Journal of Atmospheric and Oceanic Technology 23, no. 8 (2006): 1029–48. http://dx.doi.org/10.1175/jtech1903.1.

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Abstract Exact solutions of the Navier–Stokes or Euler equations of motion and the continuity equation in cylindrical coordinates for 3D, axisymmetric, inviscid, or laminar flows are utilized to represent evolving vortices that roughly model tornado cyclones or misocyclones contracting to tornadoes. These solutions are unsteady versions of the diffusive Burgers–Rott vortex and the inviscid Rankine-combined vortex. They satisfy the free-slip condition at the ground. Different vortices are obtained by choosing different values of the constant eddy viscosity and uniform horizontal convergence whi

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Coleman, Colin S. "The Stability of Swirling Jets." Publications of the Astronomical Society of Australia 8, no. 1 (1989): 38–40. http://dx.doi.org/10.1017/s1323358000022864.

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AbstractThe stability of a swirling cylindrical jet of compressible fluid is examined by performing a normal mode analysis and numerically solving the eigenvalue problem. Perturbations of the form f(r)exp[i(ωt-mϕ-kz)] are considered, where f is any fluid variable. Instabilities which are characteristic of both a non-swirling (top-hat) jet and a Rankine vortex are investigated for a particular axial wavenumber.The vortex instabilities are weak, and are found to remain weak when axial flow is present. The jet instabilities are much stronger, but axial flow is a stabilizing influence. The positiv

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Harvey, Benjamin J., Maarten H. P. Ambaum, and Xavier J. Carton. "Instability of Shielded Surface Temperature Vortices." Journal of the Atmospheric Sciences 68, no. 5 (2011): 964–71. http://dx.doi.org/10.1175/2010jas3669.1.

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Abstract The stability characteristics of the surface quasigeostrophic shielded Rankine vortex are found using a linearized contour dynamics model. Both the normal modes and nonmodal evolution of the system are analyzed and the results are compared with two previous studies. One is a numerical study of the instability of smooth surface quasigeostrophic vortices with which qualitative similarities are found and the other is a corresponding study for the two-dimensional Euler system with which several notable differences are highlighted.

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