Готові списки джерел за темами / Kutta condition

Добірка наукової літератури з теми "Kutta condition"

Автор: Grafiati

Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Kutta condition"

Xu, Cheng. "Kutta Condition for sharp edge flows." Mechanics Research Communications 25, no. 4 (July 1998): 415–20. http://dx.doi.org/10.1016/s0093-6413(98)00054-8.

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Crighton, D. G. "The Kutta Condition in Unsteady Flow." Annual Review of Fluid Mechanics 17, no. 1 (January 1985): 411–45. http://dx.doi.org/10.1146/annurev.fl.17.010185.002211.

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Wang, Youjiang. "An easy-to-implement highly efficient algorithm for nonlinear Kutta condition in boundary element method." Physics of Fluids 34, no. 12 (December 2022): 127111. http://dx.doi.org/10.1063/5.0131509.

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An easy-to-implement highly efficient algorithm for the nonlinear Kutta condition in the boundary element method is proposed. The main innovation is to pre-calculate an inverse matrix and use it to replace a solving system of equations with vector–scalar multiplication and matrix–vector multiplication. This allows calculating the Jacobian matrix in each nonlinear Kutta condition iteration with little computational effort, which is important for fast and robust convergence. The open-water characteristics of four different propellers are calculated with the linear and nonlinear Kutta conditions. The simulations show that the nonlinear Kutta condition results in more accurate open-water characteristics and more physically reasonable surface pressure distributions. In addition, the nonlinear Kutta condition takes no more than 3 extra seconds for an open-water simulation, and this extra time does not increase much with the number of simulation steps. The method proposed in this work is expected to improve the computational speed of the boundary element method while maintaining the same accuracy, or improve the accuracy with little extra computational time.

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Pierce, Allan D. "David Crighton and the unsteady Kutta condition." Journal of the Acoustical Society of America 109, no. 5 (May 2001): 2469–70. http://dx.doi.org/10.1121/1.4744766.

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Gu, Wei, Ming Wang, and Dongfang Li. "Stepsize Restrictions for Nonlinear Stability Properties of Neutral Delay Differential Equations." Abstract and Applied Analysis 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/304071.

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Анотація:

The present paper is concerned with the relationship between stepsize restriction and nonlinear stability of Runge-Kutta methods for delay differential equations. We obtain a special stepsize condition guaranteeing global and asymptotical stability properties of numerical methods. Some confirmations of the conditions on Runge-Kutta methods are illustrated at last.

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Poling, D. R., and D. P. Telionis. "The Trailing Edge of a Pitching Airfoil at High Reduced Frequencies." Journal of Fluids Engineering 109, no. 4 (December 1, 1987): 410–14. http://dx.doi.org/10.1115/1.3242681.

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Trailing edge flows are visualized for a pitching airfoil. The validity of the quasi-steady and an extension to an unsteady Kutta condition, namely the Giesing-Maskell condition are examined. A new dynamic similarity parameter is proposed. Earlier work and the present results are re-evaluated in terms of this parameter. A range is identified in which no Kutta-type condition may apply.

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Zannetti, Luca, and Alexandre Gourjii. "Two-vortex equilibrium in the flow past a flat plate at incidence." Journal of Fluid Mechanics 755 (August 14, 2014): 50–61. http://dx.doi.org/10.1017/jfm.2014.418.

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AbstractThe two-dimensional inviscid incompressible steady flow past an inclined flat plate is considered. A locus of asymmetric equilibrium configurations for vortex pairs is detected. It is shown that the flat geometry has peculiar properties compared to other geometries: (i) in order to satisfy the Kutta condition at both edges, which ensures flow regularity, the total circulation and the force acting on the plate must be zero; and (ii) the Kutta condition and the free vortex equilibrium conditions are not independent of each other. The non-existence of symmetric equilibrium configurations for an orthogonal plate is extended to more general asymmetric flows.

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Taha, Haithem, and Amir S. Rezaei. "Viscous extension of potential-flow unsteady aerodynamics: the lift frequency response problem." Journal of Fluid Mechanics 868 (April 8, 2019): 141–75. http://dx.doi.org/10.1017/jfm.2019.159.

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The application of the Kutta condition to unsteady flows has been controversial over the years, with increased research activities over the 1970s and 1980s. This dissatisfaction with the Kutta condition has been recently rejuvenated with the increased interest in low-Reynolds-number, high-frequency bio-inspired flight. However, there is no convincing alternative to the Kutta condition, even though it is not mathematically derived. Realizing that the lift generation and vorticity production are essentially viscous processes, we provide a viscous extension of the classical theory of unsteady aerodynamics by relaxing the Kutta condition. We introduce a trailing-edge singularity term in the pressure distribution and determine its strength by using the triple-deck viscous boundary layer theory. Based on the extended theory, we develop (for the first time) a theoretical viscous (Reynolds-number-dependent) extension of the Theodorsen lift frequency response function. It is found that viscosity induces more phase lag to the Theodorsen function particularly at high frequencies and low Reynolds numbers. The obtained theoretical results are validated against numerical laminar simulations of Navier–Stokes equations over a sinusoidally pitching NACA 0012 at low Reynolds numbers and using Reynolds-averaged Navier–Stokes equations at relatively high Reynolds numbers. The physics behind the observed viscosity-induced lag is discussed in relation to wake viscous damping, circulation development and the Kutta condition. Also, the viscous contribution to the lift is shown to significantly decrease the virtual mass, particularly at high frequencies and Reynolds numbers.

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Mohebbi, Farzad, and Mathieu Sellier. "On the Kutta Condition in Potential Flow over Airfoil." Journal of Aerodynamics 2014 (April 1, 2014): 1–10. http://dx.doi.org/10.1155/2014/676912.

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Анотація:

This paper proposes a novel method to implement the Kutta condition in irrotational, inviscid, incompressible flow (potential flow) over an airfoil. In contrast to common practice, this method is not based on the panel method. It is based on a finite difference scheme formulated on a boundary-fitted grid using an O-type elliptic grid generation technique. The proposed algorithm uses a novel and fast procedure to implement the Kutta condition by calculating the stream function over the airfoil surface through the derived expression for the airfoils with both finite trailing edge angle and cusped trailing edge. The results obtained show the excellent agreement with the results from analytical and panel methods thereby confirming the accuracy and correctness of the proposed method.

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Schneid, J. "A necessary condition forB-convergence of Runge-Kutta methods." BIT 30, no. 1 (March 1990): 166–70. http://dx.doi.org/10.1007/bf01932143.

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Дисертації з теми "Kutta condition"

Poling, David R. "Airfoil response to periodic disturbances: the unsteady Kutta condition." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/76166.

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Анотація:

Unsteady flow fields over a NACA 0012 at an angle of attack are investigated. The first is the classical pitching motion about the airfoil's quarter chord. The second is the flow over a fixed airfoil immersed in the wake of the pitching airfoil. Large reduced frequencies are considered. Measurements were obtained in a water tunnel by Laser-Doppler velocimetry. Ensemble-averaged velocity measurements were obtained in the vicinity of the trailing edges of both the pitching and the fixed airfoils. The flowfields in the wake and at the trailing edges of both airfoils were studied visually. The validity of the quasi-steady and an extension to an unsteady Kutta condition are examined. A new dynamic similarity parameter is proposed. An analytical method based on the dynamics of discrete vortices is employed. Numerical calculations of the flow over the fixed airfoil are compared with experimental results.
Ph. D.

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Gioulekas, Alexandros. "An alternative to the Kutta condition for high frequency, separated flows." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/42530.

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Pornsawad, Pornsarp, and Christine Böckmann. "Modified iterative Runge-Kutta-type methods for nonlinear ill-posed problems." Universität Potsdam, 2014. http://opus.kobv.de/ubp/volltexte/2014/7083/.

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This work is devoted to the convergence analysis of a modified Runge-Kutta-type iterative regularization method for solving nonlinear ill-posed problems under a priori and a posteriori stopping rules. The convergence rate results of the proposed method can be obtained under Hölder-type source-wise condition if the Fréchet derivative is properly scaled and locally Lipschitz continuous. Numerical results are achieved by using the Levenberg-Marquardt and Radau methods.

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Druon, Yann. "Etude de la propagation guidée et du rayonnement acoustiques par les conduits d'éjection de turboréacteur : Modélisations analytiques et numériques." Ecully, Ecole centrale de Lyon, 2006. http://www.theses.fr/2006ECDL0002.

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Le travail présenté dans ce mémoire porte sur la modélisation de la propagation acoustique dans les conduits d’éjection de turboréacteur et du rayonnement correspondant vers l’extérieur. Le propos est, d’une part, de développer des méthodes de calcul analytiques permettant de modéliser le problème de façon souple et rapide et, d’autre part, d’évaluer la pertinence de différentes méthodes numériques, indispensables pour tenir compte de façon plus réaliste de la géométrie du problème et des conditions aérodynamiques. L’étude s'inscrit dans une démarche d’analyse progressive, en partant de configurations simples pour intégrer les éléments de complexité physiques les uns après les autres (traitements acoustiques, géométrie complexe, écoulements uniforme et non uniforme…). À chaque étape, les résultats des différentes méthodes sont comparés et l’influence des principaux paramètres du problème est analysée. La solution de référence est donnée ici par une méthode de calcul analytique basée sur la théorie modale en conduit annulaire de section constante. Le rayonnement en champ lointain est calculé, pour un corps central tronqué sur la section de sortie, par l’approximation de la membrane bafflée, et pour un corps central infini, par la technique de Wiener-Hopf. Ce dernier modèle, en particulier, prend en compte l’influence, sur le champ de pression rayonné, d’une condition de Kutta appliquée au bord de fuite de l’éjection. À basse fréquence, les méthodes numériques BEM et FEM aboutissent aux mêmes résultats en l’absence d’écoulement. Les comparaisons entreprises avec des mesures expérimentales sont très satisfaisantes, confirmant la pertinence des modèles théoriques. Lorsqu’un écoulement uniforme est pris en compte, les méthodes BEM et FEM convergent, respectivement, vers les solutions analytiques avec et sans condition de Kutta appliquée au bord de fuite. Le comportement particulier de chacune des méthodes est attribué à la variable de base considérée dans les codes de calcul, à savoir la pression ou le potentiel acoustiques. À haute fréquence, l’approche asymptotique par sommation de faisceaux gaussiens conduit à des résultats peu satisfaisants, les limitations de la méthode étant probablement dues à l’absence de modèle de diffraction dans la formulation actuelle. Plusieurs facteurs géométriques influencent la propagation acoustique à l’intérieur du conduit d’éjection secondaire. L’élément le plus critique est la présence des bifurcations, qui entraîne des recompositions modales du champ sonore d’autant plus fortes que les ondes incidentes se propagent avec une composante azimutale élevée (rotation du champ acoustique). Un modèle analytique est développé pour rendre compte de ces recompositions modales et sa pertinence est confirmée par comparaison des résultats avec la méthode BEM. À l’extérieur des conduits, l’influence du mât-réacteur et de la forme précise du corps central sur le champ rayonné en direction du sol se révèle plus limitée. L’effet des couches de cisaillement prenant naissance aux bords de fuite de l’éjection est en revanche conséquent. La réfraction des ondes induite par une discontinuité de vitesse de part et d’autre d’une ligne de glissement (modèle de Munt) semble correctement modélisée par la méthode FEM, pourtant limitée en théorie à un modèle d’écoulement porteur irrotationnel. L’influence des gradients de densité et de température, en revanche, n’est pas bien reproduite
This work deals with the modeling of the acoustic propagation inside turbofan exhaust ducts and the corresponding radiation to the outside. The main objectives are, first, to develop analytical methods, enabling fast and flexible simulations of the problem, and second, to assess the relevance of different numerical methods, now indispensable to account for more realistic geometries and aerodynamic conditions. The study is performed following a progressive process, beginning with simplified configurations to integrate the elements of physical complexity one by one (presence of acoustic liners, realistic geometry, uniform and non-uniform mean flows…). At each stage, the results of the different methods are compared and the influence of the principal parameters is analyzed. The reference solution is given here by an analytical method based on the modal theory for annular ducts with constant cross section. The far field radiation is calculated, in the case of a hub truncated at the exit plane, using the flanged duct approximation, and for an infinite hub, with the aid of the Wiener-Hopf technique. In this last model, the possibility of vortex shedding from the duct trailing edge is included by application (or not) of a Kutta condition. At low frequency, and in the absence of mean flow, the Boundary and the Finite Element Methods (BEM and FEM) give the same results. The comparisons with measurements are also very good, confirming the relevance of the theoretical models. In the presence of a uniform mean flow, the BEM and the FEM respectively tend to the analytical solutions obtained with and without the Kutta condition imposed at the edge. The particular behavior associated to each method is thought to be related to the acoustic variable considered in the codes, i. E. Acoustic pressure or potential. At high frequency, the results of the Gaussian Beam Summation approach are found to be unsatisfactory, probably because of the absence of any diffraction model in the current code formulation. Several geometrical factors influence the acoustic propagation in the secondary exhaust duct (By-Pass). The most critical point lies in the presence of two bifurcations that induce modal redistributions increasing with the rotation of the incident wave inside the duct. An analytical model for sound propagation in a bifurcated duct is presented and validated by comparison with BEM results. Outside the ducts, the influence of the pylon and the after-body real geometry on the radiation to the ground seems to be more limited. Conversely, the effect of shear layers generated at the duct trailing edges is significant. In spite of theoretical restrictions, the waves refraction due to flow mismatches across a vortex sheet (Munt’s model) seems to be relatively well predicted by the FEM potential formulation. The impact of density or temperature gradients, however, is not well reproduced

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Touquet, Eric. "Contribution à la méthode FVTD résolue avec un schéma βγ [beta gamma] RK3 et des conditions frontières de type CFS-PML". Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/b71481f0-f4ad-44ec-91c3-0341c5fa9f9e/blobholder:0/2005LIMO0055.pdf.

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Ce travail a consisté à l’élaboration d’un code scientifique tridimensionnel basé sur la méthode numérique Volumes Finis ou FVTD. Largement utilisée en mécaniques des fluides, elle fait ses preuves en électromagnétisme où elle est capable de résoudre les équations de Maxwell dans le domaine temporel. Le maillage utilisé est de type éléments finis permettant ainsi une description conforme de la géométrie modélisée. Afin de limiter l’espace mémoire, nous présentons des expressions théoriques simplifiées pour un maillage structuré afin de construire un code numérique FVTD original utilisant l’approximation βγRK3. Un code FVTD pour des maillages non structurés est aussi développé et testé. La simulation de l’espace libre nécessite l’élaboration de conditions particulières autour du volume de calcul, nous avons donc mis en place des couches absorbantes basées sur les CFS-PMLs, autour d’un maillage cartésien mais aussi autour d’un maillage non structuré par hybridation de maillage
This work deals with the development of a three-dimensional scientific code based on the numerical method Finite Volume Time Domain (FVTD). Largely used in fluids mechanics, she is able to solve the Maxwell’s equations in the time domain. One of this advantages is the facility of construction an explicit scheme with non-center approximation to the three order in time and space. The grid used is of finites elements type allowing a conform description of the geometry. A simplifications of the theoretical expression for a uniform grid are presented to obtain a original structured numerical code with a βγ RK3 approximation. A new code for unstructured mesh is also developed and tested. The simulation of open space requires the development of boundary condition around the computional domain, we describe the implementation of the CFS-PMLs material with a FVTD in uniform grid and unstructured mesh with hybrid mesh

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Reddy, Swathi S. R. "Efficient Finite Element-Based Approaches for Solving Potential Flow Problems in Fluids." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5915.

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For many years, fluid flows have been modeled, starting from basic potential flow equations to full Navier-Stokes equations. The complexity of the flow increases as viscous effects, boundary layer, and flow separation are included in the fluid flow problem. However, at the preliminary design level, a simple technique to solve fluid flow problems becomes necessary for the quick assessment of 2-D aerodynamic concepts. Conventional panel methods have been popular in solving potential flow problems due to their ease of implementation for simple geometries such as circular bodies, airfoils, and 3-D applications such as wings. Nevertheless, the method becomes computationally expensive when a large number of boundary elements are required or for time-dependent problems. Moreover, due to established techniques such as panel methods, other methods go unexplored, or a smaller extent of literature is available. The present research aims to develop a Finite Element Method (FEM) for potential flows over a range of bluff bodies like cylinders to streamlined profiles such as airfoils. In contrast to conventional panel methods, Laplace’s equation describing the potential flow was solved here for the velocity potential function using the Galerkin method. A brief discussion on edge singularities in potential flows has also been presented using a half-cylinder case study. A novel method for implementing Kutta condition over airfoils to have a lifting flow has been investigated. Compared with other techniques such as finite difference and volume methods, the present methodology has proven to be computationally faster for airfoils with both finite angle and cusped trailing edges. The results have demonstrated excellent accuracy compared to analytical and panel methods. The present novel Kutta condition method has been extended to quasi-unsteady flows to show its ease of adaptability for various steady and time-dependent conditions. The process of vortex shedding in the wake of an airfoil and building up of forces was studied. A case study of a sudden step change in the angle of attack was considered for quasi-unsteady flow over an airfoil, and the results were in good accordance with the panel methods. Lastly, the application of the present FEM program was presented for a case of converting 2-D airfoil section data into 3-D wing data. 3-D wings with elliptic, rectangular, and trapezoidal planforms with tapering, sweep angle, and twist were considered. Mathematical formulas were derived from lifting-line theory, and an integration approach was used to calculate the aerodynamic coefficients. The results obtained are in good agreement with the experiments. Predicting data for 3-D wings from 2-D section airfoil using the present FEM program appears to be a very viable and cost-efficient method. Finally, the 2-D longitudinal profile of a sedan-type vehicle was considered to check the program's capability for evaluating geometries other than an airfoil. The present potential flow results for a sedan car and a modified sedan car were compared with the viscous model in ANSYS Fluent. It was observed that streamlining the sectional profile of the sedan would predict results closer to the real viscous flow due to minor flow separation.

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Книги з теми "Kutta condition"

Das, Arabindo. On the Kutta condition for flows around lifting aerofoils and wings. Koln: DFVLR, 1987.

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Kunta Kinte original: Catatan kopitiam. Kuala Lumpur, Malaysia: Berita Publishing, 2012.

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Jasin, A. Kadir. Biar putih tulang-- Kunta Kinte. Kuala Lumpur: Penerbit Universiti Malaya, 1998.

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Yousuff, Hussaini M., Manthey J, and Institute for Computer Applications in Science and Engineering., eds. Low-dissipation and -disperson Runge-Kutta schemes for computational acoustics. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1994.

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1974-, Kori'un Hary B., ed. Kampung kusta: Kumpulan karya jurnalistik Rida Award 2008. Pekanbaru: Yayasan Sagang, 2008.

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David, Gottlieb, Carpenter Mark H, and Institute for Computer Applications in Science and Engineering., eds. On the removal of boundary errors caused by Runge-Kutta integration of non-linear partial differential equations. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1994.

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Indonesia. Badan Pengembangan Kebudayaan dan Pariwisata., ed. Emerging from sorrow: Bali tragedy. [Jakarta]: Indonesia Culture and Tourism Board, 2002.

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Daniel, Tifa, and Bali (Indonesia : Province). Biro Humas dan Protokol., eds. Bali bombing. [Denpasar]: Bureau of Public Relations and Protocol, Bali Province Secretariat, 2003.

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D, Gottlieb, and Institute for Computer Applications in Science and Engineering., eds. A stable penalty method for the compressible Navier-Stokes equations. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1994.

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Low-dissipation and -disperson Runge-Kutta schemes for computational acoustics. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1994.

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Частини книг з теми "Kutta condition"

Hirschel, Ernst Heinrich, Arthur Rizzi, Christian Breitsamter, and Werner Staudacher. "About the Kutta Condition." In Separated and Vortical Flow in Aircraft Wing Aerodynamics, 127–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2020. http://dx.doi.org/10.1007/978-3-662-61328-3_6.

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Oshima, Koichi. "Some Remarks on the Kutta Condition." In Advances in Fluid Dynamics, 218–27. New York, NY: Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4612-3684-9_15.

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Zhang, Baoji, and Lupeng Fu. "Study on the Analysis Method of Ship Surf-Riding/Broaching Based on Maneuvering Equations." In Proceeding of 2021 International Conference on Wireless Communications, Networking and Applications, 569–75. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2456-9_58.

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AbstractIn order to understand the mechanism of the surf-riding/broaching profoundly, the four- degree- of-freedom(4DOF) maneuvering equation (surge, sway, yaw and roll) is simplified to a one- degree-of-freedom (1DOF) equation, and the fourth-order Runge-Kutta method is used to integrate a 1DOF surge equation in the time domain to analyze the two motion states of the ship during the surging and surf-riding. The critical Froude number is calculated using the Melnikov method. Taking a fishing boat as an example, the ship’s surf-riding/broaching phenomenon is simulated under the condition of wavelength-to-ship-length ratio and wave steepness, 1 and 1/10 respectively, providing technical support for the formulation of the second generation intact stability criteria.

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Rienstra, S. W. "A note on the Kutta condition in Glauert’s solution of the thin aerofoil problem." In Problems in Applied, Industrial and Engineering Mathematics, 61–69. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2440-9_5.

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Griffiths, David F., and Desmond J. Higham. "Runge–Kutta Method—I: Order Conditions." In Numerical Methods for Ordinary Differential Equations, 123–34. London: Springer London, 2010. http://dx.doi.org/10.1007/978-0-85729-148-6_9.

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Hundsdorfer, Willem, Anna Mozartova, and Valeriu Savcenco. "Monotonicity Conditions for Multirate and Partitioned Explicit Runge-Kutta Schemes." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 177–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-33221-0_11.

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Hairer, Ernst, Michel Roche, and Christian Lubich. "Order conditions of Runge-Kutta methods for index 2 systems." In Lecture Notes in Mathematics, 55–70. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/bfb0093952.

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Luan, Vu Thai, and Alexander Ostermann. "Stiff Order Conditions for Exponential Runge–Kutta Methods of Order Five." In Modeling, Simulation and Optimization of Complex Processes - HPSC 2012, 133–43. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09063-4_11.

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Steward, David R. "Analytic Elements from Complex Functions." In Analytic Element Method, 103–64. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198856788.003.0003.

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The mathematical functions associated with analytic elements may be formulated using a complex function $\Omega$ of a complex variable ${\zcomplex}$. Complex formulation of analytic elements is introduced in Section 3.1 for exact solutions obtained by embedding point elements that generate divergence, circulation, or velocity within a uniform vector field. Influence functions for analytic elements with circular geometry are obtained using Taylor and Laurent series expansions in Section 3.2, and conformal mapping extends this formulation to analytic elements with the geometry of ellipses (Section 3.3). The Courant's Sewing Theorem is employed in Section 3.4 to develop solutions for interface conditions across straight line segments, and the Joukowsky transformation extends methods to circular arcs and wings (Section 3.5), which satisfy a Kutta condition of non-singular vector field at their trailing edges. Vector fields with spatially distributed divergence and curl are formulated using the complex variable ${\zcomplex}$ with its complex conjugate $\overline{\zcomplex}$ in Section 3.6, and the complex conjugate is further employed in the Kolosov formulas (Section 3.7) to solve force deformation problems for analytic elements with traction or displacement specified boundary conditions.

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Elastic, Pantry, Toni Bakhtiar, and Jaharuddin. "An Optimal Control Problem of Knowledge Dissemination." In Advances in Human Resources Management and Organizational Development, 461–82. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-8933-4.ch022.

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In this chapter, the authors develop an optimal control model of knowledge dissemination among people in the society. The knowledge transfer system is formulated in term of compartmental model, where the society members are categorized into four classes based on knowledge acquisition and their willingness to disseminate. The model is equipped with a set of control variables for process intervening, namely technical training for ignorant-immigrants, information dissemination through social media for solitariants and enthusiants, and technical training for solitariants. Optimality conditions in terms of differential equations system was derived by using Pontryagin minimum principle leading to the characterization of optimal control strategies that minimizing the number of solitariants, enthusiants, and ignorants simultaneously with the control efforts. The sweep method and the fourth order Runge-Kutta algorithm was implemented to numerically solve the equation systems. The effectiveness of the control strategies toward a set of control scenarios was evaluated through examples.

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Тези доповідей конференцій з теми "Kutta condition"

Meyer, Rudolph. "A generalized Kutta condition for separated flow." In Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1995. http://dx.doi.org/10.2514/6.1995-2153.

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Yonemoto, Koichi, Keiichiro Takato, Hiroshi Ochi, and Satoshi Fujie. "Kutta Condition Violation in Two-Dimensional NACA0012 Airfoil at Low Reynolds Number." In 26th AIAA Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-6399.

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Ma, Can, Xinrong Su, Jinlan Gou, and Xin Yuan. "Runge-Kutta/Implicit Scheme for the Solution of Time Spectral Method." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26474.

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This paper investigates the Runge-Kutta implicit scheme applied to the solution of the time spectral method for periodic unsteady flow simulation. Several explicit and implicit time integration schemes including the Runge-Kutta scheme, Block-Jacobi SSOR (symmetric successive over relaxation)scheme and Block-Jacobi Runge-Kutta/Implicit scheme are implemented into an in-house code and applied to the time marching solution of the time spectral method. The time integration is coupled with Full Approximation Storage (FAS) type multi-grid method for convergence acceleration. The in-house code is based on the finite volume method and solves the RANS (Reynolds Averaged Navier-Stokes) equations on multi-block structured mesh. For spatial discretization the 3rd/5th order WENO (weighted essentially nonoscillatory) upwind scheme is used for reconstruction and the convective flux is computed with Roe approximate Riemann solver. The widely used one-equation Spalart-Allmaras turbulence model is used in the simulations. The time integration schemes for the solution of the time spectral method are tested with two different compressor cascades with periodically oscillating inlet boundary conditions. The first case is a low speed compressor stator with inlet flow angle varying with time. The second case is a high speed compressor rotor with inlet boundary condition profile to simulation the influence of upstream wakes. The results show that for moderate frequencies and wave mode numbers, the Block-Jacobi Runge-Kutta/Implicit scheme shows favorable convergence behavior compared to the other schemes. However, for extremely high frequencies and wave mode numbers such as in the simulation of high rotating speed compressors, the advantage of the Block-Jacobi Runge-Kutta/Implicit scheme over the explicit Runge-Kutta scheme is totally lost.

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Schultz, William W., Shounak Vinayak Bapat, and Paul W. Webb. "Directional Stability of a Neutrally Buoyant Joukowsky Foil." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41687.

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We examine the directional stability of a two-dimensional neutrally buoyant foil in an ideal fluid. To take advantage of the greatest simplicities we consider a symmetric Joukowsky airfoil and use the method of images. J.N. Newman in Marine Hydrodynamics [1] states, “For a nonlifting body with a pointed tail ... the vessel is always unstable. This situation results from the destabilizing effect of the Munk moment; in general an elongated nonlifting body will be stable only when moving broadside to the flow. Directional stability of a streamlined body depends on a tail fin, as in the case of an arrow or wind vane.” While the Munk moment on an ellipse leads to broadside stability, it does not have a Kutta condition. This Kutta condition causes many challenges to the analysis and simple computations. A symmetric Joukowsky has a “tail fin” and it is a lifting body when inclined to the flow. Instability is prevalent for many cases. We show that the stability depends on how the Kutta condition and the wake are implemented and indicate how stability may be increased by mass redistribution or manipulation of body motion. We demonstrate this with some simple experimental demonstrations and computations.

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Sharma, Mayank, Nathan A. Wukie, Matteo Ugolotti, and Mark G. Turner. "Unsteady Turbomachinery Simulations Using Harmonic Balance on a Discontinuous Galerkin Discretization." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-77204.

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The Harmonic Balance method is well suited for analyzing unsteadiness in turbomachinery flows comprised of a few dominant frequencies. A harmonic condition is imposed on the temporal derivatives through a Fourier transform operation. The solution is then reinterpreted as a time-domain problem, where several instances of time (lying within the largest period) are solved for simultaneously with the enforcement of the time-harmonic condition providing coupling between time instances. A discontinuous Galerkin discretization is used together with overset grids to provide higher-order spatial accuracy and flexibility in representing complex geometry. In this work, the discontinuous Galerkin infrastructure is extended for unsteady problems with a Harmonic Balance method and a Diagonally Implicit Runge-Kutta time-integrator. Verification results are presented for both time integration approaches in addition to results for a turbine blade with unsteadiness driven by a prescribed unsteady inlet boundary condition. Comparisons of results from the Harmonic Balance and Diagonally Implicit Runge-Kutta approaches are very close, with some small discrepancies that require further investigation. Significantly, rapid convergence from the Newton solver is obtained for the Harmonic Balance approach applied to the Euler equations for the turbine blade problem. Solutions converged by 8–10 orders of magnitude are obtained in between 5 and 16 Newton steps.

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Achkinadze, Alexander S., Aage Berg, Vladimir I. Krasilnikov, and Ivan E. Stepanov. "Numerical Analysis of Podded and Steering Systems Using a Velocity Based Source Boundary Element Method with Modified Trailing Edge." In SNAME 10th Propeller and Shafting Symposium. SNAME, 2003. http://dx.doi.org/10.5957/pss-2003-12.

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This paper describes an improved velocity based source boundary element method (HEM) as applied to modeling of podded propellers and propeller/rudder systems. The distinctive feature of the present method consists in the direct satisfaction of the Kutta-Joukowski condition on the additional Kutta panel constructed behind the realistic blade trailing edge when defining the unknown doublet strength. This Modified Trailing Edge (MTE) is also used as a tool for the approximate accounting for viscous and related effects on circulation. The integrated propulsive/steering system is simulated within the potential frameworks using the velocity field iterations method and quasi-steady approach, which assumes the simulation of a propeller in a spatially varying flow field while pod and strut(/rudder) are considered in a circumferentially averaged flow field The developed method is applied for calculation of rudder behind the operating propeller and podded units of different arrangement tested at MARINTEK (Norwegian Marine Technology Research Institute). The results of the measurements and theory/experiment comparisons are discussed.

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Yulin, Chen, Chen Kangmin, and Zhang Dangfang. "A Variational Finite Element Method for Solving the Blade-to-Blade Flow in Centrifugal Compressor’s Cascades With Splitter Blades on an Arbitrary Streamsheet of Revolution and a Mathematical Treatment to the Region Behind Cascades." In ASME 1985 Beijing International Gas Turbine Symposium and Exposition. American Society of Mechanical Engineers, 1985. http://dx.doi.org/10.1115/85-igt-148.

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A variational finite element method for solving the blade-to-blade flow in centrifugal compressor’s cascades with splitter blades on an arbitrary streamsheet of revolution is suggested in this paper. At first, the variational principles Ref.(1) is modified, then the variational principle after modification is discretized by eight node isoparametric finite elements to carry out the system of nonlinear algebraic equations for solving the velocity potential function. Finally, the flow field which agrees with Kutta condition and has an region behind the cascade of enough length has been worked out. In this paper, it has been discovered that when the region behind cascade L3 spreads too long the system of equations might become unsolvable as a suitable exit angle β2 can't be found. The linear relation between the velocity defference of the two side of the trailing edge and the exit angle β2 has been found, it shows the range of linear variation of β2 decreases with the increasing of the length of the region behind cascades, in addition, the linear variational relation between tan⁡β2 and L3 has also been obtained. The iterative computational method for the flow field with different length L3 is used to get the solution of flow field satisfying Kutta condition and with enough length L3.

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Zhang, Yining, Haochun Zhang, Yang Su, and Guangbo Zhao. "A Comparative Study of 10 Different Methods on Numerical Solving of Point Reactor Neutron Kinetics Equations." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67275.

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Point reactor neutron kinetics equations describe the time dependent neutron density variation in a nuclear reactor core. These equations are widely applied to nuclear system numerical simulation and nuclear power plant operational control. This paper analyses the characteristics of 10 different basic or normal methods to solve the point reactor neutron kinetics equations. These methods are: explicit and implicit Euler method, explicit and implicit four order Runge-Kutta method, Taylor polynomial method, power series method, decoupling method, end point floating method, Hermite method, Gear method. Three different types of step reactivity values are introduced respectively at initial time when point reactor neutron kinetics equations are calculated using different methods, which are positive reactivity, negative reactivity and higher positive reactivity. The calculation results show that (i) minor relative error can be gain after three types of step reactivity are introduced, when explicit or implicit four order Runge-Kutta method, Taylor polynomial method, power series method, end point floating method or Hermite method is taken. These methods which are mentioned above are appropriate for solving point reactor neutron kinetics equations. (ii) the relative error of decoupling method is large, under the calculation condition of this paper. When a higher reactivity is introduced, the calculation of decoupling method cannot be convergence. (iii) after three types of step reactivity are introduced respectively, the relative error of implicit Euler method is higher than any other method except decoupling method. The third highest is Gear method. (iv) when the higher reactivity is introduced, the relative error of explicit and implicit Euler method are almost coincident, and higher than any other methods obviously. (v) 4 methods are suitable for solution on these given conditions, which are implicit Runge-Kutta method, Taylor polynomial method, power series method and end point floating method, considering both the accuracy and stiffness.

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Selstad, Tyler J., and Kambiz Farhang. "An Efficient Algorithm for Computing the Steady-State Dynamic Response of High-Speed Mechanisms." In ASME 1994 Design Technical Conferences collocated with the ASME 1994 International Computers in Engineering Conference and Exhibition and the ASME 1994 8th Annual Database Symposium. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/detc1994-0244.

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Abstract An efficient method for obtaining the steady-state response of linear systems with periodically time varying coefficients is developed. The steady-state solution is obtained by dividing the fundamental period into a number of intervals and establishing, based on a fourth-order Rung-Kutta formulation, the relation between the response at the start and end of the period. Imposition of periodicity condition upon the response facilitates computation of the initial condition that yields the steady-state values in a single pass; i.e. integration over only one period. Through a practical example, the method is shown to be more accurate and computationally more efficient than other known methods for computing the steady-state response.

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Liu, Gao-Lian. "Generalized Euler’s Turbomachine Equation and Free Vortex Sheet Conditions in Separated/Cavitated Turbo-Flows." In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-171.

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In the present paper four fundamental problems in turbomachinery aerodynamic theory are studied in depth: (1) It is shown that the well–known Euler’s equation for turbomachine power is valid only for shrouded impellers. Then, a generalization of it to unshrouded impellers is carried out. (2) An equation relating the free trailing vortex distribution along the blade span to that of the swirl moment rVθ is derived, yielding a condition for the vanishing of free trailing vortex sheets. (3) The free surface conditions in separated flow are shown to be entirely different from those in cavitated flow. (4) Generlized Kutta conditions for 3–D rotor bladings in separated and caviated flows are also derived. All these results are of fundamental value in both analytical and numerical handlings of fully 3–D rotor–flows.

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