A partir de cette page vous pouvez :
Retourner au premier écran avec les étagères virtuelles... |
Résultat de la recherche
14 résultat(s) recherche sur le mot-clé 'VORTICES'
Affiner la recherche Faire une suggestion
Tip Vortex Cavitation Characteristics and Delay of Inception on a Three-Dimensional Hydrofoil / William G. Souders
contenu dans David W. Taylor Naval Ship Research And Development Center Bethesda Report
Titre : Tip Vortex Cavitation Characteristics and Delay of Inception on a Three-Dimensional Hydrofoil Type de document : articles et extraits Auteurs : William G. Souders, Auteur ; G. P. Platzer, Auteur Editeur : David W Taylor Naval Ship Research And Development Center Bethesda Année de publication : 1981 Collection : Technical report num. DTNSRDC-81/007 Importance : 68 p. Langues : Anglais (eng) Mots-clés : VORTICES CAVITATION HYDROFOILS SURFACE ROUGHNESS ANGLE OF ATTACK FLOW VISUALIZATION THREE DIMENSIONAL DELAY REYNOLDS NUMBER HYDRODYNAMIC CONFIGURATIONS LIFTING SURFACES.ZVORTICES CAVITATION HYDROFOILS SURFACE ROUGHNESS ANGLE OF ATTACK FLOW VISUALIZATION THREE DIMENSIONAL DELAY REYNOLDS NUMBER HYDRODYNAMIC CONFIGURATIONS LIFTING SURFACES Résumé : A research program was conducted to investigate both the fundamental aspects of, and techniques for delaying, tip vortex cavitation on a three-dimensional hydrofoil. The specific concepts considered for delaying tip vortex cavitation included: a bulbous tip, an artificially roughened tip, and a mass injected tip. The experiments were conducted in the David W. Taylor Naval Ship Research and Development Center 24-inch cavitation tunnel, where the effects of the various concepts on both foil tip vortex cavitation inception and performance were established. These measurements were made at a Reynolds number R subscript c, based on root chord length, of approximately 5,000,000. Some of the more fundamental aspects of the tip vortex rollup process have been documented through the use of flow visualization techniques. The results for the tip vortex cavitation delay concepts indicate substantial increases in the tip vortex cavitation inception speed relative to the unaltered tip; i.e., a 94 percent increase for the roughened tip, 38 percent for the bulbous tip, and 54 percent and 33 percent for the active and passive mass injected respectively. These results were obtained over a wide range of foil angle of attack and with little or no measurable loss in foil performance; i.e., no measurable lift decrease or drag increase.
contenu dans David W. Taylor Naval Ship Research And Development Center Bethesda Report
Tip Vortex Cavitation Characteristics and Delay of Inception on a Three-Dimensional Hydrofoil [articles et extraits] / William G. Souders, Auteur ; G. P. Platzer, Auteur . - David W Taylor Naval Ship Research And Development Center Bethesda, 1981 . - 68 p.. - (Technical report; DTNSRDC-81/007) .
Langues : Anglais (eng)
Mots-clés : VORTICES CAVITATION HYDROFOILS SURFACE ROUGHNESS ANGLE OF ATTACK FLOW VISUALIZATION THREE DIMENSIONAL DELAY REYNOLDS NUMBER HYDRODYNAMIC CONFIGURATIONS LIFTING SURFACES.ZVORTICES CAVITATION HYDROFOILS SURFACE ROUGHNESS ANGLE OF ATTACK FLOW VISUALIZATION THREE DIMENSIONAL DELAY REYNOLDS NUMBER HYDRODYNAMIC CONFIGURATIONS LIFTING SURFACES Résumé : A research program was conducted to investigate both the fundamental aspects of, and techniques for delaying, tip vortex cavitation on a three-dimensional hydrofoil. The specific concepts considered for delaying tip vortex cavitation included: a bulbous tip, an artificially roughened tip, and a mass injected tip. The experiments were conducted in the David W. Taylor Naval Ship Research and Development Center 24-inch cavitation tunnel, where the effects of the various concepts on both foil tip vortex cavitation inception and performance were established. These measurements were made at a Reynolds number R subscript c, based on root chord length, of approximately 5,000,000. Some of the more fundamental aspects of the tip vortex rollup process have been documented through the use of flow visualization techniques. The results for the tip vortex cavitation delay concepts indicate substantial increases in the tip vortex cavitation inception speed relative to the unaltered tip; i.e., a 94 percent increase for the roughened tip, 38 percent for the bulbous tip, and 54 percent and 33 percent for the active and passive mass injected respectively. These results were obtained over a wide range of foil angle of attack and with little or no measurable loss in foil performance; i.e., no measurable lift decrease or drag increase. Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité ART-1981007 SOU Document imprimé Bureau chercheur Bureau de Christophe Clanet Disponible ACTIVE CONTROL TECHNOLOGY : APPLICATIONS AND LESSONS LEARNED.(Les technologies du système de contrôle actif : applications et enseignements).
Titre : ACTIVE CONTROL TECHNOLOGY : APPLICATIONS AND LESSONS LEARNED.(Les technologies du système de contrôle actif : applications et enseignements). Type de document : document imprimé Editeur : ONERA Année de publication : 34700 Collection : (AGARD-CP-560). Importance : 420,00 ISBN/ISSN/EAN : 92-8360-007-X Langues : Français (fre) Mots-clés : ACTIVE CONTROL AEROELASTICITY DESIGN FIGHTER AIRCRAFT FLIGHT CONTROL FLIGHT MANEUVERS FLYING QUALITIES FUZZI CONTROL VORTICES Note de contenu : The Flight Mechanics Panel Symposium held in Turin, Italy, from 9-13 May 94
ACTIVE CONTROL TECHNOLOGY : APPLICATIONS AND LESSONS LEARNED.(Les technologies du système de contrôle actif : applications et enseignements). [document imprimé] . - ONERA, 34700 . - 420,00. - ((AGARD-CP-560).) .
ISBN : 92-8360-007-X
Langues : Français (fre)
Mots-clés : ACTIVE CONTROL AEROELASTICITY DESIGN FIGHTER AIRCRAFT FLIGHT CONTROL FLIGHT MANEUVERS FLYING QUALITIES FUZZI CONTROL VORTICES Note de contenu : The Flight Mechanics Panel Symposium held in Turin, Italy, from 9-13 May 94
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2308 Document imprimé Bureau chercheur Indéterminé Disponible AERODYNAMIC THEORY : DIV A-D, vol. 1. / DURAND W.F.
Titre : AERODYNAMIC THEORY : DIV A-D, vol. 1. Type de document : document imprimé Auteurs : DURAND W.F., Auteur Editeur : California Institute of Technology Année de publication : 26665 Importance : 398,00 Langues : Français (fre) Mots-clés : 3-D FIELDS AERO STATICS ELLIPSOID FLOW FLUID MECHANIC VORTICES Note de contenu : General Review of Progress Under a Grant of the Guggenheim Fund for the Promotion of Aeronautics
AERODYNAMIC THEORY : DIV A-D, vol. 1. [document imprimé] / DURAND W.F., Auteur . - [S.l.] : California Institute of Technology, 26665 . - 398,00.
Langues : Français (fre)
Mots-clés : 3-D FIELDS AERO STATICS ELLIPSOID FLOW FLUID MECHANIC VORTICES Note de contenu : General Review of Progress Under a Grant of the Guggenheim Fund for the Promotion of Aeronautics
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA0139 Document imprimé Bureau chercheur Indéterminé Disponible AERODYNAMICS AND AEROACOUSTICS OF ROTORCRAFT.(l'Aérodynamique et l'aéroacoustique des aéronefs à voilure tournante).
Titre : AERODYNAMICS AND AEROACOUSTICS OF ROTORCRAFT.(l'Aérodynamique et l'aéroacoustique des aéronefs à voilure tournante). Type de document : document imprimé Editeur : ONERA Année de publication : 34912 Collection : (AGARD-CP-552). Importance : 508,00 ISBN/ISSN/EAN : 92-8360-015-0 Langues : Français (fre) Mots-clés : ACOUSTICS AEROACOUSTICS AERODYNAMICS COMPUTATIONAL FLUID DYNAMICS HELICOPTERS NOISE ROTARY WING AIRCRAFT ROTORS VORTICES WIND TURBINES Note de contenu : 75th Fluid Dynamics Symposium held in Berlin, Germany, 10-13 October 94
AERODYNAMICS AND AEROACOUSTICS OF ROTORCRAFT.(l'Aérodynamique et l'aéroacoustique des aéronefs à voilure tournante). [document imprimé] . - ONERA, 34912 . - 508,00. - ((AGARD-CP-552).) .
ISBN : 92-8360-015-0
Langues : Français (fre)
Mots-clés : ACOUSTICS AEROACOUSTICS AERODYNAMICS COMPUTATIONAL FLUID DYNAMICS HELICOPTERS NOISE ROTARY WING AIRCRAFT ROTORS VORTICES WIND TURBINES Note de contenu : 75th Fluid Dynamics Symposium held in Berlin, Germany, 10-13 October 94
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2306 Document imprimé Bureau chercheur Indéterminé Disponible FLUID DYNAMICS RESEARCH ON SUPERSONIC AIRCRAFT. (Les Travaux de Recherche en Dynamique des Fluides Relatifs aux Aéronefs Supersoniques).
Titre : FLUID DYNAMICS RESEARCH ON SUPERSONIC AIRCRAFT. (Les Travaux de Recherche en Dynamique des Fluides Relatifs aux Aéronefs Supersoniques). Type de document : document imprimé Auteurs : Von Karman Institute for Fluid Dynamics (VKI), Organisateur de congrès Editeur : RTO/NATO Année de publication : 36100 Collection : (RTO Educational Notes 4). Importance : 332,00 ISBN/ISSN/EAN : 92-8371-007-X Langues : Français (fre) Mots-clés : AERODYNAMICS COMPUTATIONAL FLUID DYNAMICS DRAG FLUID DYNAMICS LAMINAR FLOW LIFT SONIC BOOM SUPERSONIC AIRCRAFT TURBULENT BOUNDARY LAYER VORTICES Note de contenu : BP 25, 7 Rue Ancelle 92201 Neuilly-sur-Seine
FLUID DYNAMICS RESEARCH ON SUPERSONIC AIRCRAFT. (Les Travaux de Recherche en Dynamique des Fluides Relatifs aux Aéronefs Supersoniques). [document imprimé] / Von Karman Institute for Fluid Dynamics (VKI), Organisateur de congrès . - RTO/NATO, 36100 . - 332,00. - ((RTO Educational Notes 4).) .
ISBN : 92-8371-007-X
Langues : Français (fre)
Mots-clés : AERODYNAMICS COMPUTATIONAL FLUID DYNAMICS DRAG FLUID DYNAMICS LAMINAR FLOW LIFT SONIC BOOM SUPERSONIC AIRCRAFT TURBULENT BOUNDARY LAYER VORTICES Note de contenu : BP 25, 7 Rue Ancelle 92201 Neuilly-sur-Seine
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA3812 Document imprimé Bureau chercheur Indéterminé Disponible HIGH SPEED BODY MOTION IN WATER. (Le Mouvement des Corps Evoluant à Grande Vitesse dans l'Eau).
Titre : HIGH SPEED BODY MOTION IN WATER. (Le Mouvement des Corps Evoluant à Grande Vitesse dans l'Eau). Type de document : document imprimé Editeur : ONERA Année de publication : 35827 Collection : AGARD report Importance : 352,00 ISBN/ISSN/EAN : 92-8361-071-7 Note générale : Agard
Langues : Français (fre) Mots-clés : BOUNDARY LAYER FLOW CAVITATION COMPUTERIZED SIMULATION HYDRODYNAMICS HYDROFOILS HYDROMECHANICS PROPULSION SHEAR FLOW TURBULENT BOUNDARY LAYER VORTICES Note de contenu : This Report is a Compilation of the Proceedings of a Fluid Dynamics Panel Workshop
HIGH SPEED BODY MOTION IN WATER. (Le Mouvement des Corps Evoluant à Grande Vitesse dans l'Eau). [document imprimé] . - ONERA, 35827 . - 352,00. - (AGARD report) .
ISBN : 92-8361-071-7
Agard
Langues : Français (fre)
Mots-clés : BOUNDARY LAYER FLOW CAVITATION COMPUTERIZED SIMULATION HYDRODYNAMICS HYDROFOILS HYDROMECHANICS PROPULSION SHEAR FLOW TURBULENT BOUNDARY LAYER VORTICES Note de contenu : This Report is a Compilation of the Proceedings of a Fluid Dynamics Panel Workshop
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA3039 Document imprimé Bureau chercheur Indéterminé Disponible Introduction to fluid dynamics / E.B Jnr. McLEOD
Titre : Introduction to fluid dynamics Type de document : document imprimé Auteurs : E.B Jnr. McLEOD, Auteur Editeur : Pergamon Press Année de publication : 1963 Importance : 229,00 Langues : Français (fre) Mots-clés : BERNOULLI'S EQUATIONS COMPRESSIBLE FLUIDS DIMENSIONAL FLOWS DYNAMIC EQUATIONS IRROTATIONAL MOTION RECTILINEAR VORTICES Index. décimale : 47 Fluid dynamics Introduction to fluid dynamics [document imprimé] / E.B Jnr. McLEOD, Auteur . - [S.l.] : Pergamon Press, 1963 . - 229,00.
Langues : Français (fre)
Mots-clés : BERNOULLI'S EQUATIONS COMPRESSIBLE FLUIDS DIMENSIONAL FLOWS DYNAMIC EQUATIONS IRROTATIONAL MOTION RECTILINEAR VORTICES Index. décimale : 47 Fluid dynamics Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité O0046 47 MCL Document imprimé IRPHE Bibliothèque de l'IRPHE Disponible MANOEUVRING AERODYNAMICS. (La Manoeuvrabilité par l'Aérodynamique).
Titre : MANOEUVRING AERODYNAMICS. (La Manoeuvrabilité par l'Aérodynamique). Type de document : document imprimé Editeur : ONERA Année de publication : 33573 Collection : (AGARD-CP-497). Importance : 292,00 ISBN/ISSN/EAN : 92-8350-643-X Langues : Français (fre) Mots-clés : AERODYNAMIC FORCES ANGLE OF ATTACK FLIGHT CONTROL FLIGHT MANEUVERS FLIGHT TESTS UNSTEADY FLOW VORTICES Note de contenu : Fluid Dynamics Panel Specialists' Meeting held in Toulouse, France 1st-2nd May 91
MANOEUVRING AERODYNAMICS. (La Manoeuvrabilité par l'Aérodynamique). [document imprimé] . - ONERA, 33573 . - 292,00. - ((AGARD-CP-497).) .
ISBN : 92-8350-643-X
Langues : Français (fre)
Mots-clés : AERODYNAMIC FORCES ANGLE OF ATTACK FLIGHT CONTROL FLIGHT MANEUVERS FLIGHT TESTS UNSTEADY FLOW VORTICES Note de contenu : Fluid Dynamics Panel Specialists' Meeting held in Toulouse, France 1st-2nd May 91
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2353 Document imprimé Bureau chercheur Indéterminé Disponible ROUND TABLE DISCUSSION ON MODELLING OF TIME-VARIANT FLOWS USING VORTEX DYNAMICS.
Titre : ROUND TABLE DISCUSSION ON MODELLING OF TIME-VARIANT FLOWS USING VORTEX DYNAMICS. Type de document : document imprimé Editeur : ONERA Année de publication : 31809 Collection : (AGARD-AR-239). Importance : 104,00 ISBN/ISSN/EAN : 92-8350-405-4 Langues : Français (fre) Mots-clés : COMPRESSIBLE FLOW FLUID DYNAMICS MATHEMATICAL MODELS VORTICES VISCOUS FLOW ROUND TABLE DISCUSSION ON MODELLING OF TIME-VARIANT FLOWS USING VORTEX DYNAMICS. [document imprimé] . - ONERA, 31809 . - 104,00. - ((AGARD-AR-239).) .
ISBN : 92-8350-405-4
Langues : Français (fre)
Mots-clés : COMPRESSIBLE FLOW FLUID DYNAMICS MATHEMATICAL MODELS VORTICES VISCOUS FLOW Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2429 Document imprimé Bureau chercheur Indéterminé Disponible SPECIAL COURSE ON AIRCRAFT DYNAMICS AT HIGH ANGLES OF ATTACK : EXPERIMENTS AND MODELLING. (La Dynamique de Vol des Aéronefs aux Grands Angles d'Attaque : Experimentation et Modélisation).
Titre : SPECIAL COURSE ON AIRCRAFT DYNAMICS AT HIGH ANGLES OF ATTACK : EXPERIMENTS AND MODELLING. (La Dynamique de Vol des Aéronefs aux Grands Angles d'Attaque : Experimentation et Modélisation). Type de document : document imprimé Editeur : ONERA Année de publication : 33298 Collection : (AGARD-R-776). Importance : 146,00 ISBN/ISSN/EAN : 92-8350-607-3 Langues : Français (fre) Mots-clés : AERODYNAMICS CONFIGURATIONS AEROFOILS AIRCRAFT FLIGHT TESTS FLUID DYNAMICS FLUID FLOW MATHEMATICAL MODELS VORTICES WINDS TUNNELS Note de contenu : NASA Langley Research Center, Hampton, Virginia 23665, United States, 8th to 11th April 91 and at the von Karman Institute, Rhode-Saint-Genèse, Belgium, 22nd to 25th April 91
SPECIAL COURSE ON AIRCRAFT DYNAMICS AT HIGH ANGLES OF ATTACK : EXPERIMENTS AND MODELLING. (La Dynamique de Vol des Aéronefs aux Grands Angles d'Attaque : Experimentation et Modélisation). [document imprimé] . - ONERA, 33298 . - 146,00. - ((AGARD-R-776).) .
ISBN : 92-8350-607-3
Langues : Français (fre)
Mots-clés : AERODYNAMICS CONFIGURATIONS AEROFOILS AIRCRAFT FLIGHT TESTS FLUID DYNAMICS FLUID FLOW MATHEMATICAL MODELS VORTICES WINDS TUNNELS Note de contenu : NASA Langley Research Center, Hampton, Virginia 23665, United States, 8th to 11th April 91 and at the von Karman Institute, Rhode-Saint-Genèse, Belgium, 22nd to 25th April 91
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2362 Document imprimé Bureau chercheur Indéterminé Disponible SPECIALISTS MEETING ON HELICOPTER ROTOR LOADS PREDICTION METHODS.
Titre : SPECIALISTS MEETING ON HELICOPTER ROTOR LOADS PREDICTION METHODS. Type de document : document imprimé Editeur : ONERA Année de publication : 26877 Collection : (AGARD-CP-122). Importance : 160,00 Langues : Français (fre) Mots-clés : AERODYNAMICS LOADS COMPUTERIZED CONFIGURATIONS HELICOPTERS MATHEMATICAL MODELS PREDICTIONS ROTARY WINGS SIMULATION VORTICES Note de contenu : 36th Meeting of the structures and Materials Panel
SPECIALISTS MEETING ON HELICOPTER ROTOR LOADS PREDICTION METHODS. [document imprimé] . - ONERA, 26877 . - 160,00. - ((AGARD-CP-122).) .
Langues : Français (fre)
Mots-clés : AERODYNAMICS LOADS COMPUTERIZED CONFIGURATIONS HELICOPTERS MATHEMATICAL MODELS PREDICTIONS ROTARY WINGS SIMULATION VORTICES Note de contenu : 36th Meeting of the structures and Materials Panel
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2534 Document imprimé Bureau chercheur Indéterminé Disponible THE CHARACTERISATION & MODIFICATION OF WAKES FROM LIFTING VEHICLES IN FLUIDS. (La Caractérisation et la Modification des Sillages Crées dans les Fluides par des Véhicules Portant).
Titre : THE CHARACTERISATION & MODIFICATION OF WAKES FROM LIFTING VEHICLES IN FLUIDS. (La Caractérisation et la Modification des Sillages Crées dans les Fluides par des Véhicules Portant). Type de document : document imprimé Editeur : ONERA Année de publication : 35370 Collection : (AGARD-CP-584). Importance : 428,00 ISBN/ISSN/EAN : 92-8360-034-7 Langues : Français (fre) Mots-clés : AERODYNAMICSTABILITY AIR TRAFIC CONTROL AIRCRAFT COMPUTATIONAL FLUID DYNAMICS DETECTION REVIEWS ROLL SEPARATION VORTICES WAKE DETECTION WAKES THE CHARACTERISATION & MODIFICATION OF WAKES FROM LIFTING VEHICLES IN FLUIDS. (La Caractérisation et la Modification des Sillages Crées dans les Fluides par des Véhicules Portant). [document imprimé] . - ONERA, 35370 . - 428,00. - ((AGARD-CP-584).) .
ISBN : 92-8360-034-7
Langues : Français (fre)
Mots-clés : AERODYNAMICSTABILITY AIR TRAFIC CONTROL AIRCRAFT COMPUTATIONAL FLUID DYNAMICS DETECTION REVIEWS ROLL SEPARATION VORTICES WAKE DETECTION WAKES Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité MA2550 Document imprimé Bureau chercheur Indéterminé Disponible THE KARMAN STREET OF VORTICES IN A CHANNEL OF FINITE BREADTH. / ROSENHEAD.
Titre : THE KARMAN STREET OF VORTICES IN A CHANNEL OF FINITE BREADTH. Type de document : document imprimé Auteurs : ROSENHEAD., Auteur Année de publication : 47286 Langues : Français (fre) Mots-clés : FINITE BREADTH VORTICES Index. décimale : 47.15 Laminar flows, Laminar boundary layers Note de contenu : Rosenhead,university of leeds
THE KARMAN STREET OF VORTICES IN A CHANNEL OF FINITE BREADTH. [document imprimé] / ROSENHEAD., Auteur . - 47286.
Langues : Français (fre)
Mots-clés : FINITE BREADTH VORTICES Index. décimale : 47.15 Laminar flows, Laminar boundary layers Note de contenu : Rosenhead,university of leeds
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité OA0017 47.15 ROS Document imprimé IRPHE Indéterminé Disponible Geophysical and astrophysical fluid dynamics, Vol.70 No.1-4. The stability of barotropic vortices - implications for tropical cyclone motion / H. C. Weber
in Geophysical and astrophysical fluid dynamics
Titre de série : Geophysical and astrophysical fluid dynamics, Vol.70 No.1-4 Titre : The stability of barotropic vortices - implications for tropical cyclone motion Type de document : articles et extraits Auteurs : H. C. Weber, Auteur ; R. K. Smith, Auteur Année de publication : 1993 Importance : p.1-30 ISBN/ISSN/EAN : 0309-1929 Langues : Français (fre) Mots-clés : BAROTROPIC VORTICES MODEL SHALLOW WATER SHALLOW-WATER SHEAR-FLOW TROPICAL CYCLONES VORTEX Résumé : We investigate the existence of normal mode perturbations to barotropic vortices defined by tangential velocity profiles that have been used in recent studies of tropical cyclone motion. For this purpose we have developed a new procedure, more accurate than previous ones, to search systematically for the eigensolutions. Linear stability analyses are carried out both for vortices in a nondivergent barotropic model and for those in a shallow water model, in each case using cylindrical coordinates on an f-plane. The nondivergent barotropic vorticity equation is used to determine the normal modes of a range of continuous vortex profiles with zero relative circulation at infinity. All profiles were found to be stable at azimuthal wavenumber one, the neutral nonrotating mode found by Michalke and Timme (1967) being the only mode that exists. At higher wavenumbers no normal modes were found except for an unstable mode of wavenumber two for a profile used by Smith and Ulrich (1990) that decays relatively rapidly with radius. However, the growth rate of this mode is relatively small. Accordingly, our results justify an assumption made by Smith and Ulrich (1990) and Smith (1991) in the development of an analytic theory for tropical cyclone motion. Our analysis of the vortex profile of Chan and Williams (1987) and the discontinuous profiles of willoughby (1988) differs considerably from that of Peng and Williams (1991) who obtained eigenvalues that were strongly dependent on the radial resolution of their solution method. However, our results are qualitatively consistent, showing differences between 5% and 10%, with those of Gent and McWilliams (1986) for the range of profiles they studied. The shallow water model is applied to reexamine the stability of the Gaussian streamfunction profile studied by Flatau and Stevens (1989), a calculation of possible relevance to instabilities of the tropical cyclone outflow layer. Flatau and Stevens' model equations were found to be incomplete. When the terms missing from their equations are included, the results of the eigenfunction analysis are very different. In a control experiment using the incomplete equations, the results of Flatau and Stevens were qualitatively reproduced, but with quantitative differences up to 20%. Application of our method to the two vortex profiles studied by Willoughby (1990) gave quantitatively and qualitatively different results in comparison with Willoughby's findings. The implications of the existence of neutral or unstable normal modes for vortex motion in nondivergent barotropic models are discussed with reference to recent analytical studies of tropical cyclone motion. The existence of the nonrotating neutral wavenumber one mode in numerical vortex models is found to arise because of inaccuracy in the centre-location of the vortex in analogy with the results obtained by Sutyrin and Flierl (1991) for discontinuous vorticity profiles. The excitation of a wavenumber two mode produces no track deviation by nonlinear interaction in nondivergent barotropic models. Unstable and neutral wavenumber one modes that rotate were found only for the vortex profiles studied by Willoughby (1988, 1990). The excitation of such modes could be expected to lead to the cycloidal motion of such a vortex.
in Geophysical and astrophysical fluid dynamics
Geophysical and astrophysical fluid dynamics, Vol.70 No.1-4. The stability of barotropic vortices - implications for tropical cyclone motion [articles et extraits] / H. C. Weber, Auteur ; R. K. Smith, Auteur . - 1993 . - p.1-30.
ISSN : 0309-1929
Langues : Français (fre)
Mots-clés : BAROTROPIC VORTICES MODEL SHALLOW WATER SHALLOW-WATER SHEAR-FLOW TROPICAL CYCLONES VORTEX Résumé : We investigate the existence of normal mode perturbations to barotropic vortices defined by tangential velocity profiles that have been used in recent studies of tropical cyclone motion. For this purpose we have developed a new procedure, more accurate than previous ones, to search systematically for the eigensolutions. Linear stability analyses are carried out both for vortices in a nondivergent barotropic model and for those in a shallow water model, in each case using cylindrical coordinates on an f-plane. The nondivergent barotropic vorticity equation is used to determine the normal modes of a range of continuous vortex profiles with zero relative circulation at infinity. All profiles were found to be stable at azimuthal wavenumber one, the neutral nonrotating mode found by Michalke and Timme (1967) being the only mode that exists. At higher wavenumbers no normal modes were found except for an unstable mode of wavenumber two for a profile used by Smith and Ulrich (1990) that decays relatively rapidly with radius. However, the growth rate of this mode is relatively small. Accordingly, our results justify an assumption made by Smith and Ulrich (1990) and Smith (1991) in the development of an analytic theory for tropical cyclone motion. Our analysis of the vortex profile of Chan and Williams (1987) and the discontinuous profiles of willoughby (1988) differs considerably from that of Peng and Williams (1991) who obtained eigenvalues that were strongly dependent on the radial resolution of their solution method. However, our results are qualitatively consistent, showing differences between 5% and 10%, with those of Gent and McWilliams (1986) for the range of profiles they studied. The shallow water model is applied to reexamine the stability of the Gaussian streamfunction profile studied by Flatau and Stevens (1989), a calculation of possible relevance to instabilities of the tropical cyclone outflow layer. Flatau and Stevens' model equations were found to be incomplete. When the terms missing from their equations are included, the results of the eigenfunction analysis are very different. In a control experiment using the incomplete equations, the results of Flatau and Stevens were qualitatively reproduced, but with quantitative differences up to 20%. Application of our method to the two vortex profiles studied by Willoughby (1990) gave quantitatively and qualitatively different results in comparison with Willoughby's findings. The implications of the existence of neutral or unstable normal modes for vortex motion in nondivergent barotropic models are discussed with reference to recent analytical studies of tropical cyclone motion. The existence of the nonrotating neutral wavenumber one mode in numerical vortex models is found to arise because of inaccuracy in the centre-location of the vortex in analogy with the results obtained by Sutyrin and Flierl (1991) for discontinuous vorticity profiles. The excitation of a wavenumber two mode produces no track deviation by nonlinear interaction in nondivergent barotropic models. Unstable and neutral wavenumber one modes that rotate were found only for the vortex profiles studied by Willoughby (1988, 1990). The excitation of such modes could be expected to lead to the cycloidal motion of such a vortex.
Réservation
Réserver ce document
Exemplaires
Code-barres Cote Support Localisation Section Disponibilité ART-7348-0 ART Document imprimé Bureau chercheur Bureau de LE DIZES Stéphane Disponible