4,096 research outputs found

    Simulation of 2-dimensional viscous flow through cascades using a semi-elliptic analysis and hybrid C-H grids

    Get PDF
    A semi-elliptic formulation, termed the interacting parabolized Navier-Stokes (IPNS) formulation, is developed for the analysis of a class of subsonic viscous flows for which streamwise diffusion is neglible but which are significantly influenced by upstream interactions. The IPNS equations are obtained from the Navier-Stokes equations by dropping the streamwise viscous-diffusion terms but retaining upstream influence via the streamwise pressure-gradient. A two-step alternating-direction-explicit numerical scheme is developed to solve these equations. The quasi-linearization and discretization of the equations are carefully examined so that no artificial viscosity is added externally to the scheme. Also, solutions to compressible as well as nearly compressible flows are obtained without any modification either in the analysis or in the solution process. The procedure is applied to constricted channels and cascade passages formed by airfoils of various shapes. These geometries are represented using numerically generated curilinear boundary-oriented coordinates forming an H-grid. A hybrid C-H grid, more appropriate for cascade of airfoils with rounded leading edges, was also developed. Satisfactory results are obtained for flows through cascades of Joukowski airfoils

    Analysis of two-dimensional incompressible flow past airfoils using unsteady Navier-Stokes equations

    Get PDF
    The conservative form of the unsteady Navier-Stokes equations in terms of vorticity and stream function in generalized curvilinear coordinates are used to analyze the flow structure of steady separation and unsteady flow with massive separation. The numerical method solves the discretized equations using an ADI-BGE method. The method is applied to a symmetric 12 percent thick Joukowski airfoil. A conformal clustered grid is generated; several 1-D stretching transformations are used to obtain a grid that attempts to resolve many of the multiple scales of the unsteady flow with massive separation, while maintaining the transformation metrics to be smooth and continuous in the entire flow field. Detailed numerical results are obtained for three flow configurations (1) Re = 1000, alpha = 5 deg., (2) Re =1000, alpha = 15 deg., (3) Re = 10,000, alpha = 5 deg. No artificial dissipation was added; however, lack of a fine grid in the normal direction has presently led to results which are considered qualitative, especially for case (3)

    Simulation of self-induced unsteady motion in the near wake of a Joukowski airfoil

    Get PDF
    The unsteady Navier-Stokes analysis is shown to be capable of analyzing the massively separated, persistently unsteady flow in the post-stall regime of a Joukowski airfoil for an angle of attack as high as 53 degrees. The analysis has provided the detailed flow structure, showing the complex vortex interaction for this configuration. The aerodynamic coefficients for lift, drag, and moment were calculated. So far only the spatial structure of the vortex interaction was computed. It is now important to potentially use the large-scale vortex interactions, an additional energy source, to improve the aerodynamic performance

    Boundary-fitted coordinates for regions with highly curved boundaries and reentrant boundaries

    Get PDF
    A procedure was developed using the differential equation approach for generating boundary fitted coordinates for regions with highly curved boundaries as well as reentrant boundaries, such as those encountered in breaking surface waves. The resulting coordinates are nearly orthogonal and can provide adequate resolution even in the reentrant region. Consistent treatment of end boundaries and the use of a systematic initialization scheme and advanced implicit numerical solution techniques make the procedure highly efficient. The method developed for implicit enforcement of the periodicity boundary condition should be beneficial in the analysis of turbomachinery flow applications

    Una traccia machiavelliana nelle pagine del Quijote

    Get PDF
    Tra le pieghe dello straordinario percorso del Quijote si trova un passaggio la cui ascendenza risale a Machiavelli. C’è poi da riflettere sull’origine di quelle righe divertite e incisive, per cercar di capire se Cervantes abbia proprio letto le pagine del Principe, oppure se sia pervenuto per via indiretta alle idee che lì espone. Appunto per misurare il grado di curiosità e di competenza da parte di Cervantes in fatto di lingua e di scrittori italiani, si getta qui uno sguardo sulla sua familiarità con il filone irriverente e burlesco della letteratura «toscana» del ‘500. D’altro canto, la traccia machiavelliana che si trova nel Quijote, documenta l’interesse per Machiavelli e per le sue idee, ma non fa di Cervantes un «machiavellico ». Nemmeno si può dire che egli sia orientato contro le idee del Fiorentino in virtù di un’opposizione morale o teologica. La distanza tra i due nasce piuttosto dal fatto che Cervantes —come Montaigne— è tra i grandi fondatori di una nuova dimensione del moderno, che si lascia alle spalle le certezze antropocentriche del Rinascimento, mentre fa emergere una diversa immagine dell’uomo: si fa strada infatti, fino ad occupare il primo piano, l’interiorità della dimensione privata, secondo una prospettiva ben diversa da quel primato dell’uomo pubblico che è nota dominante nelle opere machiavellianeBetween the lines, of the amazing literary work Quijote, we find a passage that brings to mind Machiavelli. In these entertaining and incisive lines, there is quite a bit of food for thought to make us reflect whether Cervantes had actually read pages from the Prince or if his ideas had come to him through other means. Therefore, in order to measure Cervantes’s degree of curiosity and competence regarding Italian and Italian writers, in this paper we take a glance at Cervantes’s familiarity with the irreverent and burlesque line of thought in Tuscan literature belonging to the 1500s. The traces and hints of familiarity with Machiavelli found in Quijote document Cervantes’s interest in the Italian writer and his ideas, however these points do not make Cervantes a Machiavellian. In any case, we can not affirm that Cervantes was oriented against the Florentine’s ideas considering his moral and theological beliefs. The difference between the two arises from the fact that Cervantes as Montaigne is among the founding fathers of a new dimension of Modern man, that leaves behind the anthropocentric certainties of the Renaissance, and promotes the emergence of a different image of Man, which arises from the interiority of the private dimension, an outlook in stark opposition to the Public Figure known as the dominant theme in Machiavelli’s works

    Sobre Cervantes, Manzoni y Sciascia. Breve historia de un equívoco acerca del itinerario de la palabra “mafia"

    Get PDF
    En un artículo de 1986 Leonardo Sciascia propone la hipótesis de un origen español de la palabra “mafia”, apoyándose en la lectura que Alessandro Manzoni hace de El Quijote. Ahora bien, en toda la obra de Cervantes la palabra no resulta. El artículo indaga este curioso caso hasta hallar la solución al equívoco en un error de transcripción que se ha perpetuado en el tiempo hasta 1990, y que perdura hasta hoy en el imaginario de los lectores de Sciasc

    Pengaruh Pengendalian Intern dan Kompetensi Sumber Daya Manusia Terhadap Keandalan Laporan Keuangan Pemerintah Daerah : studi pada OPD Kabupaten Karawang

    Get PDF
    Penelitian ini bertujuan untuk mengetahui bagaimana pengaruh pengendalian intern dan kompetensi sumber daya manusia terhadap keandalan laporan keuangan pemerintah daerah di Pemerintah Kabupaten Karawang. Variabel independen dalam penelitian ini adalah pengendalian intern dan kompetensi sumber daya manusia, serta variabel dependennya adalah keandalan laporan keuangan pemerintah daerah. Metode penelitian yang digunakan adalah metode penelitian asosiatif. Populasi dalam penelitian ini adalah seluruh Organisasi Perangkat Daerah di Pemerintah Kabupaten Karawang. Sampel yang digunakan yaitu sebanyak 24 responden dengan menggunakan teknik sampel jenuh. Metode analisis yang digunakan adalah analisis regresi berganda. Data yang dikumpulkan diolah dengan menggunakan SPSS versi 20.0. Hasil penelitian ini menunjukkan bahwa: (1) pengendalian intern berpengaruh positif terhadap keandalan pelaporan keuangan pemerintah daerah di Pemerintah Kabupaten Karawang; (2) kompetensi sumber daya manusia berpengaruh positif terhdap keandalan laporan keuangan pemerintah daerah di Pemerintah Kabupaten Karawang; (3) pengendalian intern dan kompetensi sumber daya manusia berpengaruh terhadap keandalan laporan Keuangan Pemerintah di Pemerintah Kabupaten Karawang. The purposes of this research are to know the influence of Internal Control and Human Resources Competence Toward The Reliability of Financial Reporting of Local Government in Karawang District Government. The independent variables of this study were internal control and human resources competence, moreover the dependent variable was the reliability of financial reporting of local government. The research method used here is assosiatif research method. Population in this study were all regional working units device in Karawang District Government. Sample obtained were 24 respondents used census sampling. The analysis method used is multiple regression analysis. The data collected were processed using SPSS version 20.0. The result of this research are: (1) there is positive influence between internal control and the reliability of financial reporting of local government in Karawang District Government; (2) there is positive influence between human resources competence and the reliability of financial reporting of local government in Karawang District Government; (3) simultaneously internal control and human resources competence are influence toward the reliability of financial reporting of local government in Karawang District Government
    • …