Journal articles: 'Navire marchand'

1

Mutgé i Vives, Josefina. "Contribució a l'estudi del comerç al Mediterrani Occidental en el segle XIV: l'atac piràtic a la coca d'Esteve Bordell." Anuario de Estudios Medievales 24, no. 1 (April 2, 2020): 465. http://dx.doi.org/10.3989/aem.1994.v24.985.

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L'article étudie la prise perpétrée par des pirates Génois en août 1322 du navire d'Esteve Bordell, marchand et citoyen Barcelonais, lorsqu'il retournait de Chypre, chargé de marchandises destinées à Barcelone. Dans l'article on analyse aussi la répercussion diplomatique de cet événement et les negociations ardues arrangées par les "consellers" barcelonais pour obtenir des Génois la restitution des dommages et intérêts.

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Nordman, Daniel. "La mémoire d'un captif." Annales. Histoire, Sciences Sociales 41, no. 6 (December 1986): 1397–418. http://dx.doi.org/10.3406/ahess.1986.283356.

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Il arrive qu'un beau livre soit d'abord un récit. Voici alors, au début du XVIIIesiècle, un gamin d'Anglais qui, à l'école de Penryn, en Cornouailles, ne goûte guère la sévérité de son maître. Il préfère bientôt suivre son oncle qui commande à bord d'un navire marchand à destination de Gênes. Courte expérience : à son retour, le bateau, au large de la Galice, est pris par les corsaires de Salé. Amenés au Maroc, les prisonniers sont conduits à Meknès. L'enfant — comme tous les captifs de cette époque — est remis au sultan Moulay Ismaïl. Il finit par se convertir — malgré lui, précise-t-il — , apprend la langue et l'écriture arabes. Il est, à nouveau, retiré de l'école et chargé des jardins, puis, au service d'une des reines, des clefs des appartements royaux. Le portier gagne la confiance du sultan.

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Heers, Jacques. "Gênes et l’Afrique du Nord Vers 1450: les voyages «per costeriam»." Anuario de Estudios Medievales 21, no. 1 (April 2, 2020): 233. http://dx.doi.org/10.3989/aem.1991.v21.1109.

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Toutes les nations maritimes de la rive Nord de la Méditerranée s'intéressent au commerce avec le Maghreb et y exercent diverses activités. Mais toutes n'agissent pas de la même façon et la ville de Gênes semble, dans ce secteur, avoir suivi une politique très particulière. Les trafics entre Gênes et le Maghreb bénéficiaient, au XVème siècle, d'une sorte de paix: peu d'actes de piraterie, peu de représailles, peu de captures d'esclaves; dans Gênes, les esclaves en provenance du Maghreb sont très rares et les marchands ou patrons de navires s'emploient volontiers aux rachats des captifs. L'originalité du système de navigation réside dans les voyages que les notaires appellent «per costeriam»; c’est à dire, de longs pépriples maritimes qui, pour de très gros navires, vont directement d'Angleterre en Orient (ou réciproquement) en longeant la côte d'Afrique, sans remonter vers le Nord et faire escale à Gênes: économie de temps et d'argent. Pour ces voyages le parran de navire dispose d'une très grande initiative et assume de grandes responsabilités: navigation, chargements et déchargements des balles de marchandises (en particulier des draps englais), mais aussi et surtout ventes de ces produits. Ceci implique un nombre important d'escales sur le littoral du Maghreb (parfois au large d'une simple plage) et, aussi, la fréquentation de nombreux marchés ou de négociants musulmans. Ces trafics «per costeriam» sont de véritables aventures et les capitaines des navires y ont acquis une grande expérience des mers, des côtes, des populations étrangères à leur monde chrétien.

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Bosher, J. F. "Sept grands marchands catholiques français participant au commerce avec la Nouvelle-France (1660-1715)." Revue d'histoire de l'Amérique française 48, no. 1 (August 26, 2008): 3–27. http://dx.doi.org/10.7202/305298ar.

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RÉSUMÉ Pendant le règne de Louis XIV, sept grands marchands français de religion catholique s'imposèrent dans le commerce avec la Nouvelle-France à un moment où les marchands huguenots armaient de moins en moins de navires. On a souvent exagéré le rôle de ces derniers marchands pendant cette période, et il est probable que leur importance ait diminué à la suite des persécutions dont ils ont été victimes pendant les guerres de 1689 à 1713. En effet, la monarchie se montrait très méfiante à leur égard, une situation dont les marchands catholiques ont pu bénéficier. D'origine modeste, les sept marchands catholiques qui sont l'objet de notre étude ont été favorisés par cinq facteurs : des mariages avantageux, des relations solides de famille ou d'affaires outre-Atlantique, des rapports étroits avec des membres du clergé ou des officiers métropolitains (dans un cas au moins) et des occasions d'affaires issues des guerres de Louis XIV. Malheureusement, ces marchands subirent de lourdes pertes financières, assez fréquentes en ces années, car les Bourbons ne payaient pas toujours leurs dettes.

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Clochard, Olivier. "Enfermés à bord des navires de la marine marchande." Annales de géographie 702-703, no. 2 (2015): 185. http://dx.doi.org/10.3917/ag.702.0185.

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6

Srinivas, K. "An explicit spatial marching algorithm for Navier-Stokes equations." Computers & Fluids 21, no. 2 (April 1992): 291–99. http://dx.doi.org/10.1016/0045-7930(92)90026-r.

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7

Kwon, O. K. "Navier–Stokes Solution for Steady Two-Dimensional Transonic Cascade Flows." Journal of Turbomachinery 110, no. 3 (July 1, 1988): 339–46. http://dx.doi.org/10.1115/1.3262202.

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A robust, time-marching Navier–Stokes solution procedure based on the explicit hopscotch method is presented for solution of steady, two-dimensional, transonic turbine cascade flows. The method is applied to the strong conservation form of the unsteady Navier–Stokes equations written in arbitrary curvilinear coordinates. Cascade flow solutions are obtained on an orthogonal, body-conforming “O” grid with the standard k–ε turbulence model. Computed results are presented and compared with experimental data.

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Davis, R. L., D. E. Hobbs, and H. D. Weingold. "Prediction of Compressor Cascade Performance Using a Navier–Stokes Technique." Journal of Turbomachinery 110, no. 4 (October 1, 1988): 520–31. http://dx.doi.org/10.1115/1.3262226.

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An explicit, time marching, multiple-grid Navier–Stokes technique is demonstrated for the prediction of quasi-three-dimensional turbomachinery compressor cascade performance over the entire incidence range. A numerical investigation has been performed in which the present Navier–Stokes procedure was used to analyze a series of compressor cascade viscous flows for which corresponding experimental data are available. Results from these calculations show that the current viscous flow procedure is capable of predicting cascade profile loss and airfoil pressure distributions with high accuracy. The results from this numerical investigation in the form of comparisons between the predicted profile loss, exit gas angle, and pressure distributions with experimental data are presented in this paper. Results from a grid refinement study are also shown to demonstrate that the Navier–Stokes solutions are grid independent.

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Liu, Xuezong, and R. H. Pletcher. "A Coupled Marching Procedure for the Partially Parabolized Navier-Stokes Equations." Numerical Heat Transfer, Part B: Fundamentals 10, no. 6 (1986): 539–56. http://dx.doi.org/10.1080/10407798608552523.

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Liu, Xuezong, and R. H. Pletcher. "A COUPLED MARCHING PROCEDURE FOR THE PARTIALLY PARABOLIZED NAVIER-STOKES EQUATIONS." Numerical Heat Transfer 10, no. 6 (December 1986): 539–56. http://dx.doi.org/10.1080/10407788608913534.

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11

Soh, W. Y. "Time-marching solution of incompressible Navier-Stokes equations for internal flow." Journal of Computational Physics 70, no. 1 (May 1987): 232–52. http://dx.doi.org/10.1016/0021-9991(87)90012-x.

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12

Cravero, C., and A. Satta. "Comparison of Semi-Empirical Correlations and a Navier-Stokes Method for the Overall Performance Assessment of Turbine Cascades." Journal of Fluids Engineering 125, no. 2 (March 1, 2003): 308–14. http://dx.doi.org/10.1115/1.1539869.

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Turbomachinery flows can nowadays be investigated using several numerical techniques to solve the full set of Navier-Stokes equations; nevertheless the accuracy in the computation of losses is still a challenging topic. The paper describes a time-marching method developed by the authors for the integration of the Reynolds averaged Navier-Stokes equations in turbomachinery cascades. The attention is focused on turbine sections and the computed aerodynamic performances (outlet flow angle, profile loss, etc.,) are compared to experimental data and/or correlations. The need for this kind of CFD analysis tools is stressed for the substitution of standard correlations when a new blade is designed.

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He, L., and J. D. Denton. "Three-Dimensional Time-Marching Inviscid and Viscous Solutions for Unsteady Flows Around Vibrating Blades." Journal of Turbomachinery 116, no. 3 (July 1, 1994): 469–76. http://dx.doi.org/10.1115/1.2929436.

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A three-dimensional nonlinear time-marching method of solving the thin-layer Navier–Stokes equations in a simplified form has been developed for blade flutter calculations. The discretization of the equations is made using the cell-vertex finite volume scheme in space and the four-stage Runge–Kutta scheme in time. Calculations are carried out in a single-blade-passage domain and the phase-shifted periodic condition is implemented by using the shape correction method. The three-dimensional unsteady Euler solution is obtained at conditions of zero viscosity, and is validated against a well-established three-dimensional semi-analytical method. For viscous solutions, the time-step limitation on the explicit temporal discretization scheme is effectively relaxed by using a time-consistent two-grid time-marching technique. A transonic rotor blade passage flow (with tip-leakage) is calculated using the present three-dimensional unsteady viscous solution method. Calculated steady flow results agree well with the corresponding experiment and with other calculations. Calculated unsteady loadings due to oscillations of the rotor blades reveal some notable three-dimensional viscous flow features. The feasibility of solving the simplified thin-layer Navier–Stokes solver for oscillating blade flows at practical conditions is demonstrated.

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Vradis, G., V. Zalak, and J. Bentson. "Simultaneous Variable Solutions of the Incompressible Steady Navier-Stokes Equations in General Curvilinear Coordinate Systems." Journal of Fluids Engineering 114, no. 3 (September 1, 1992): 299–305. http://dx.doi.org/10.1115/1.2910030.

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A simultaneous variable solution technique for the incompressible, steady, two-dimensional Navier-Stokes equations in primitive formulation and general curvilinear orthogonal and nonorthogonal coordinate systems has been developed. The governing equations are discretized using finite difference approximations. The formulation is fully second order accurate and the well-known staggered grid of Welch and Harlow is used. The solution algorithm is based on an iterative marching technique in which the algebraic equations are linearized by evaluating the coefficients at the previous iteration level. The resulting system of linear equations is solved in a marching fashion by employing a block tridiagonal solution algorithm to obtain the solution along lines transverse to the main flow direction. The strong pressure-velocity coupling inherent in the present formulation results in high convergence rates. Flows in channels of different geometries have been computed and the results have been compared to available data in the literature. In all cases the method has demonstrated to be accurate, robust and computationally efficient.

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15

Zheng, Y., and L. He. "Multigrid upwind Euler/Navier-Stokes computation on adaptive unstructured meshes." Aeronautical Journal 105, no. 1046 (April 2001): 173–84. http://dx.doi.org/10.1017/s0001924000025410.

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Abstract An unstructured flow solver with adaptive mesh refinement and multigrid acceleration is developed to efficiently compute two-dimensional inviscid and viscous steady flows about complex configurations. High resolution is achieved by using the upwind scheme coupled with adaptive mesh refinement. An aspect-ratio adaptive multigrid method is developed and applied to effectively accelerate the solution convergence of the explicit time-marching in the near wall regions with high aspect mesh ratios. Numerical examples are presented for configurations and conditions ranging from transonic to low speed flows to demonstrate accuracy, speed, and robustness of the method.

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TenPas, P. W., and R. H. Pletcher. "Coupled space-marching method for the Navier-Stokes equations for subsonic flows." AIAA Journal 29, no. 2 (February 1991): 219–26. http://dx.doi.org/10.2514/3.10567.

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SRINIVAS, K. "AN EXPLICIT FINITE VOLUME SPATIAL MARCHING METHOD FOR REDUCED NAVIER-STOKES EQUATIONS." International Journal for Numerical Methods in Fluids 22, no. 2 (January 30, 1996): 121–35. http://dx.doi.org/10.1002/(sici)1097-0363(19960130)22:2<121::aid-fld266>3.0.co;2-p.

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Xi, Rui, Zhan Ling Ji, Hong Guang Jia, and Qian Jin Xiao. "Time Marching Simulation of Aeroelasticity Based on a Coupled Numerical Method." Applied Mechanics and Materials 610 (August 2014): 60–64. http://dx.doi.org/10.4028/www.scientific.net/amm.610.60.

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A numerical method integrating computational fluid dynamics and computational structural dynamics for predicating wing flutter in time domain is described. A strong coupling employing the dual-time method is adopted. The Newmark algorithm is used to solve flutter equation in modal spaces while the finite-volume algorithm for the Navier-Stokes equations is used to solve the flow. The computed flutter boundaries of AGARD wing 445.6 for frees-tream Mach numbers ranging from 0.499 to 1.141 agree well with the experiment than using the DLM.

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Boulanger, Patrick. "Sur la ligne de la mer Noire, des navires marchands français à Odessa (1875-1915)." Cahiers slaves 14, no. 1 (2016): 135–59. http://dx.doi.org/10.3406/casla.2016.1141.

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Ning, W., Y. S. Li, and R. G. Wells. "Predicting Bladerow Interactions Using a Multistage Time-Linearized Navier-Stokes Solver." Journal of Turbomachinery 125, no. 1 (January 1, 2003): 25–32. http://dx.doi.org/10.1115/1.1516570.

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A multistage frequency domain (time-linearized/nonlinear harmonic) Navier-Stokes unsteady flow solver has been developed for predicting unsteady flows induced by bladerow interactions. In this paper, the time-linearized option of the solver has been used to analyze unsteady flows in a subsonic turbine test stage and the DLR transonic counter-rotating shrouded propfan. The numerical accuracy and computational efficiency of the time-linearized viscous methods have been demonstrated by comparing predictions with test data and nonlinear time-marching solutions for these two test cases. It is concluded that the development of efficient frequency domain approaches enables unsteady flow predictions to be used in the design cycles to tackle aeromechanics problems.

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Reddy, D. R., and S. G. Rubin. "Consistent Boundary Conditions for Reduced Navier-Stokes (RNS) Scheme Applied to Three-Dimensional Viscous Flows." Journal of Fluids Engineering 110, no. 3 (September 1, 1988): 306–14. http://dx.doi.org/10.1115/1.3243549.

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A consistent and efficient set of boundary conditions are developed for the multi-sweep space marching pressure-elliptic Reduced Navier-Stokes (RNS) scheme as applied for three-dimensional internal viscous flow problems. No-slip boundary conditions are directly imposed on the solid walls. There is no iteration procedure required in the cross plane to ensure mass conservation across each marching plane. The finite difference equations forming the coefficient matrix are ordered such that the surface normal velocity is specified on all the solid walls; unlike external flows, a pressure boundary condition in the cross plane is not required. Since continuity is directly satisfied at all points in the flow domain, the first order momentum equations can be solved directly for the pressure without the need for a Poisson pressure correction equation. The procedure developed herein can also be applied with periodic boundary conditions. The analysis is given for general compressible flows. Incompressible flow solutions are obtained, for straight and curved ducts of square cross section, to validate the procedure. The solutions of these test cases are used to demonstrate the applicability of the RNS scheme, with the improved boundary conditions, for internal flows with strong interaction as would be encountered in ducts and turbomachinery geometries.

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Dorney, D. J., and R. L. Davis. "Navier–Stokes Analysis of Turbine Blade Heat Transfer and Performance." Journal of Turbomachinery 114, no. 4 (October 1, 1992): 795–806. http://dx.doi.org/10.1115/1.2928033.

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A three-dimensional Navier–Stokes analysis of heat transfer and aerodynamic performance is presented for a low-speed linear turbine cascade. The numerical approach used in this analysis consists of an alternate-direction, implicit, approximate-factorization, time-marching technique. An objective of this investigation has been to establish the computational grid density requirements necessary to predict blade surface and endwall heat transfer accurately, as well as the exit plane aerodynamic total pressure loss and flow angle distributions. In addition, a study has been performed to determine the importance of modeling transition as well as a viable implementation strategy for the three-dimensional turbulence model in the turbine blade passage. Results are presented demonstrating that the present procedure can accurately predict three-dimensional turbine blade heat transfer as well as the absolute level and spanwise distribution of aerodynamic performance quantities.

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23

Brière, Jean-François. "Le commerce triangulaire entre les ports Terre-Neuviers français, les pêcheries d’Amérique du Nord et Marseille au 18e siècle : nouvelles perspectives." Revue d'histoire de l'Amérique française 40, no. 2 (August 20, 2008): 193–214. http://dx.doi.org/10.7202/304443ar.

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RÉSUMÉ Grâce à une documentation exceptionnellement riche, constituée de la correspondance entre des armateurs granvillais et malouins avec un des principaux consignataires marseillais, pour la vente des cargaisons de morue sèche au 18e siècle, la maison Roux, cet article analyse le commerce triangulaire reliant les ports du Ponant, le Canada et Marseille. Ce commerce qui occupait 30 à 45 bâtiments par saison en temps de paix avec des arrivages annuels d'une valeur de deux à quatre millions de livres atteint, au 18e siècle, un haut degré de complexité où le succès de la campagne dépendait de la rapidité aussi bien des navires qui devaient boucler leur périple triangulaire dans l'année que de l'échange d'informations commerciales. Les nombreuses et fréquentes lettres échangées entre les armateurs et le consignataire révèlent les espoirs, les inquiétudes et les déceptions de ces hommes d'affaires et permettent une analyse microéconomique des conditions dans lesquelles se déroulait ce trafic. En soulignant les risques énormes encourus par les marchands, l'article met également en évidence l'importance du consignataire qui non seulement vendait le poisson et s'occupait de trouver une cargaison de retour, mais aussi prenait souvent part aux armements et assurait les navires.

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Kirtley, K. R., and B. Lakshminarayana. "Computation of Three-Dimensional Turbulent Turbomachinery Flows Using a Coupled Parabolic-Marching Method." Journal of Turbomachinery 110, no. 4 (October 1, 1988): 549–56. http://dx.doi.org/10.1115/1.3262230.

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A new coupled parabolic-marching method was developed to compute the three-dimensional turbulent flow in a turbine endwall cascade, a compressor cascade wake, and an axial flow compressor rotor passage. The method solves the partially parabolized incompressible Navier–Stokes equation and continuity in a coupled fashion. The continuity equation was manipulated using pseudocompressibility theory to give a convergent algorithm for complex geometries. The computed end-wall boundary layers and secondary flow compared well with the experimental data for the turbine cascade as did the wake profiles for the compressor cascade using a k–ε turbulence model. Suction side boundary layers, pressure distributions, and exit stagnation pressure losses compared reasonably well with the data for the compressor rotor.

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Boudin, Laurent, Céline Grandmont, Bérénice Grec, Sébastien Martin, Amina Mecherbet, and Frédérique Noël. "Fluid-kinetic modelling for respiratory aerosols with variable size and temperature." ESAIM: Proceedings and Surveys 67 (2020): 100–119. http://dx.doi.org/10.1051/proc/202067007.

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In this paper, we propose a coupled fluid-kinetic model taking into account the radius growth of aerosol particles due to humidity in the respiratory system. We aim to numerically investigate the impact of hygroscopic effects on the particle behaviour. The air flow is described by the incompressible Navier-Stokes equations, and the aerosol by a Vlasov-type equation involving the air humidity and temperature, both quantities satisfying a convection-diffusion equation with a source term. Conservations properties are checked and an explicit time-marching scheme is proposed. Twodimensional numerical simulations in a branched structure show the influence of the particle size variations on the aerosol dynamics.

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Wei, D. Y. C., B. Farouk, and D. Apelian. "Melting Powder Particles in a Low-Pressure Plasma Jet." Journal of Heat Transfer 109, no. 4 (November 1, 1987): 971–76. http://dx.doi.org/10.1115/1.3248212.

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A numerical model has been developed to predict the temperature history of metal particles injected in a low-pressure (supersonic) d-c plasma jet. The temperature and velocity fields of the plasma jet are predicted by solving the parabolized compressible Navier–Stokes equations using a spatial marching scheme. Particle trajectories and heat transfer characteristics are calculated using the predicted plasma jet temperature and velocity fields. Correction factors have been introduced to take into account the noncontinuum effects encountered in the low-pressure environment. The plasma jet profiles as well as the particle/plasma interactions under different jet pressure ratios (from underexpanded to overexpanded cases) have been investigated.

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Walker, P. J., and W. N. Dawes. "The Extension and Application of Three-Dimensional Time-Marching Analyses to Incompressible Turbomachinery Flows." Journal of Turbomachinery 112, no. 3 (July 1, 1990): 385–90. http://dx.doi.org/10.1115/1.2927671.

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Conventional time-marching flow solvers perform poorly when integrating compressible flow equations at low Mach number levels. This is shown to be due to unfavorable interaction between long-wavelength errors and the inflow and outflow boundaries. Chorin’s method of artificial compressibility is adopted to extend the range of Denton’s inviscid flow solver and Dawes’ three-dimensional Navier–Stokes solver to zero Mach number flows. The paper makes a new contribution by showing how to choose the artificial acoustic speed systematically to optimize convergence rate with regard to the error wave–boundary interactions. Applications to a turbine rotor and generic water pump geometry are presented.

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Nakajima, K., Y. Kallinderis, I. Sibetheros, R. W. Miksad, and K. Lambrakos. "A Numerical Study of the Hydrodynamics of Reversing Flows Around a Cylinder." Journal of Offshore Mechanics and Arctic Engineering 116, no. 4 (November 1, 1994): 202–8. http://dx.doi.org/10.1115/1.2920152.

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A numerical study of the nonlinear and random behavior of flow-induced forces on offshore structures and experimental verification of the results are presented. The numerical study is based on a finite-element method for the unsteady incompressible Navier-Stokes equations in two dimensions. The momentum equations combined with a pressure correction equation are solved employing fourth-order artificial dissipation with a nonstaggered grid, instead of the more commonly used staggered meshes. The solution is advanced in time with a combined explicit and implicit marching scheme. Emphasis is placed on study of reversing flows around a cylinder. Comparisons with experimental data evaluate accuracy and robustness of the method.

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He, L., and K. Sato. "Numerical Solution of Incompressible Unsteady Flows in Turbomachinery." Journal of Fluids Engineering 123, no. 3 (April 5, 2000): 680–85. http://dx.doi.org/10.1115/1.1383595.

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A three-dimensional incompressible viscous flow solver of the thin-layer Navier-Stokes equations was developed for the unsteady turbomachinery flow computations. The solution algorithm for the unsteady flows combines the dual time stepping technique with the artificial compressibility approach for solving the incompressible unsteady flow governing equations. For time accurate calculations, subiterations are introduced by marching the equations in the pseudo-time to fully recover the incompressible continuity equation at each real time step, accelerated with a multi-grid technique. Computations of test cases show satisfactory agreements with corresponding theoretical and experimental results, demonstrating the validity and applicability of the present method to unsteady incompressible turbomachinery flows.

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Holman, H. T. "“Altogether Unproductive of Profit”: A History of the First Prince Edward Island Steam Navigation Company." Northern Mariner / Le marin du nord 30, no. 1 (June 10, 2021): 23–44. http://dx.doi.org/10.25071/2561-5467.83.

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La Prince Edward Island Steam Navigation Company a été créée afin d’assurer des communications fiables et en temps opportun entre les colonies du détroit de Northumberland, dans le sud du golfe du Saint-Laurent. Fondée en 1842, la société bénéficiait d’un vaste soutien communautaire de la part des constructeurs de navires et des marchands et, plus important encore, de la participation du gouvernement de la colonie en tant que propriétaire. Bien que la participation directe du gouvernement colonial ait fourni le capital nécessaire à l’entreprise, les attentes en matière de service aux ports non rentables ont entravé la capacité de la société de gérer ses opérations et ont contribué à son échec après cinq ans. Malgré son quasi-monopole sur le service de navigationà vapeur dans la région, la société était vouée à l’échec en raison de la capacité excédentaire et des coûts d’exploitation élevés.

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Maneuvrier, Christophe, Michel Daeffler, and Isabelle Bretthauer. "Les importations de bois de Brésil en Normandie dans la première moitié du XVIe siècle." Revista Portuguesa de História 49 (January 3, 2019): 189–213. http://dx.doi.org/10.14195/0870-4147_49_8.

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La découverte de nouveaux documents issus d’archives judiciaires permet de mieux appréhender l’organisation des voyages des ports normands vers le Brésil. Les départs avaient généralement lieu à l’automne ou au début de l’hiver, les retours s’effectuant durant l’été. Pour réduire les risques et échapper auxflottes portugaises, les navires voyageaient en convois, souvent de trois à cinq navires dont les caractéristiques peuvent être présentées grâce à plusieurs contrats de construction conservés dans des registres notariés. La mise en oeuvre de ces expéditions nécessitait d’importants capitaux rassemblés par desmarchands rouennais. Parmi eux, figurent plusieurs familles d’origine espagnole de niveau international qui pouvaient parfois s’associer avec des investisseurs de Paris, de Lyon, ou de Champagne. Les quantités de bois‑brésil rapportées en Normandie étaient considérables. Une partie de ces marchandises fut très tôt réexpédiée à Paris, la Rochelle et jusqu’à Anvers, Rouen étant alors un entrepôt international de tout premier ordre. Le bois‑brésilétait utilisé comme produit tinctorial mais aussi dans l’architecture, notamment au château de Fontainebleau (demeure favorite de François Ier), ainsi que dans la fabrication de meubles ou de petits objets de luxe. Ces sources nouvelles montrent enfin que les expéditions des frères Verrazzano n’ont pas ouvert la route du Brésil aux marchands français, mais que ces échanges ont commencé beaucoup plus tôt, même si une accélération de ce trafic est probable au cours de la décennie 1520.

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Johnstone, Eleanor C., and Philip Hall. "Free-stream coherent structures in the unsteady Rayleigh boundary layer." IMA Journal of Applied Mathematics 85, no. 6 (October 9, 2020): 1021–40. http://dx.doi.org/10.1093/imamat/hxaa038.

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Abstract Results are presented for nonlinear equilibrium solutions of the Navier–Stokes equations in the boundary layer set up by a flat plate started impulsively from rest. The solutions take the form of a wave–roll–streak interaction, which takes place in a layer located at the edge of the boundary layer. This extends previous results for similar nonlinear equilibrium solutions in steady 2D boundary layers. The results are derived asymptotically and then compared to numerical results obtained by marching the reduced boundary-region disturbance equations forward in time. It is concluded that the previously found canonical free-stream coherent structures in steady boundary layers can be embedded in unbounded, unsteady shear flows.

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33

Shi, Feng, Guoping Liang, Yubo Zhao, and Jun Zou. "New Splitting Methods for Convection-Dominated Diffusion Problems and Navier-Stokes Equations." Communications in Computational Physics 16, no. 5 (November 2014): 1239–62. http://dx.doi.org/10.4208/cicp.031013.030614a.

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AbstractWe present a new splitting method for time-dependent convention-dominated diffusion problems. The original convention diffusion system is split into two sub-systems: a pure convection system and a diffusion system. At each time step, a convection problem and a diffusion problem are solved successively. A few important features of the scheme lie in the facts that the convection subproblem is solved explicitly and multistep techniques can be used to essentially enlarge the stability region so that the resulting scheme behaves like an unconditionally stable scheme; while the diffusion subproblem is always self-adjoint and coercive so that they can be solved efficiently using many existing optimal preconditioned iterative solvers. The scheme can be extended for solving the Navier-Stokes equations, where the nonlinearity is resolved by a linear explicit multistep scheme at the convection step, while only a generalized Stokes problem is needed to solve at the diffusion step and the major stiffness matrix stays invariant in the time marching process. Numerical simulations are presented to demonstrate the stability, convergence and performance of the single-step and multistep variants of the new scheme.

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34

He, L. "Three-dimensional unsteady Navier—Stokes analysis of stator—rotor interaction in axial-flow turbines." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 214, no. 1 (February 1, 2000): 13–22. http://dx.doi.org/10.1243/0957650001537813.

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A three-dimensional full Navier-Stokes method is developed and applied to calculations of unsteady flows through multiple blade rows in axial-flow turbomachinery. The solver adopts the cellcentred finite volume discretization and the four-stage Runge-Kutta time-marching scheme. Unsteady calculations are effectively accelerated by using a time-consistent multi-grid technique, resulting in a speed-up by a factor of 10–20 with adequate temporal accuracy. The computational efficiency and validity of the present multi-grid technique are illustrated by comparisons with the results of the conventional dual time-stepping scheme. Calculated unsteady pressures on blade surfaces for a turbine stage performances at different stator-rotor axial gaps reveals a marked three-dimensional behaviour of the interaction between incoming wakes and rotor passage-vortex structures. The time-averaged losses from unsteady calculations show a noticeable spanwise redistribution compared with the steady results. Two dimensional and three-dimensional calculations indicate opposite trends in stage efficiency variation when the stator—rotor gap is reduced.

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35

Lee, Y.-K., S. Raghunathan, E. Benard, H.-D. Kim, and T. Setoguchi. "Control of plume interference effects on axisymmetric afterbodies." Aeronautical Journal 108, no. 1082 (April 2004): 185–96. http://dx.doi.org/10.1017/s0001924000000099.

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Plume interference effects on the axisymmetric flowfields around powered missiles are investigated using computational techniques. The study is mainly to understand the physics of the plume-induced shock and separation particularly at high plume to exit pressure ratios with and without shock-turbulent boundary layer control methods. Mass-averaged Navier-Stokes equations with the RNG k-ε turbulence model are solved using a fully implicit finite volume scheme and time-marching algorithm. The shock position and extent of separation was found to be dependent on the freestream Mach number and plume pressure ratio. Rounding the tail or a groove on the surface near the tail moved the shockwave downstream of the tail fin which should enhance the control of the missile.

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36

Gehrer, A., and H. Jericha. "External Heat Transfer Predictions in a Highly Loaded Transonic Linear Turbine Guide Vane Cascade Using an Upwind Biased Navier–Stokes Solver." Journal of Turbomachinery 121, no. 3 (July 1, 1999): 525–31. http://dx.doi.org/10.1115/1.2841347.

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External heat transfer predictions are performed for two-dimensional turbine blade cascades. The Reynolds-averaged Navier–Stokes equations with algebraic (Arnone and Pacciani, 1998), one-equation (Spalart and Allmaras, 1994), and two-equation (low-Re k–ε, Biswas and Fukuyama, 1994) turbulence closures are solved with a fully implicit time-marching finite volume method. Comparisons with measurements (Arts et al., 1990; Arts, 1994) for a highly loaded transonic turbine nozzle guide vane cascade show good agreement in some cases, but also reveal problems with transition prediction and turbulence modeling. Special attention has been focused on the low-Re k–ε model concerning the influence of the inlet boundary condition for the ε-equation and problems in the stagnation point region.

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37

Lee, S. H., and Tzuyin Wu. "Drag Force on a Sphere Moving in Low-Reynolds-Number Pipe Flows." Journal of Mechanics 23, no. 4 (December 2007): 423–32. http://dx.doi.org/10.1017/s1727719100001477.

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AbstractIn this paper, the drag force on a sphere moving constantly along the centerline of a circular pipe filled with viscous fluid (the falling-sphere problem) under low Reynolds number condition is investigated via numerical calculation. The incompressible Navier-Stokes equations are formulated in a pseudocompressibility form. The numerical scheme makes use of finite-volume method and the numerical flux terms are evaluated using the Total-Variation Diminishing (TVD) strategy commonly applied to the compressible flow. Steady solution is obtained by marching (iterating) in time until the artificial time derivative of pressure term in the continuity equation drops to zero.In the calculation, six different Reynolds number (Re) ranging from 0.1 to 1 and seven different pipe-to-sphere diameter ratios (D/d) ranging from 5 to 40 are selected to study the pipe-wall effect. In each case, the drag force on the sphere is evaluated and the results are compared with the existing approximate theoretical values derived from correcting the Stokes' formula. Both results agree in trend, but with noticeable deviation in values, particularly for cases with large pipe-to-sphere diameter ratios. The deviation is due to the fact that theoretical values were based on the solution to the linearized Navier-Stokes equations (Stokes' creeping-flow equations), while the fully nonlinear form of the Navier-Stokes equations are adopted in the present calculations. Finally, a least-square regression technique is applied to collapse the calculated results into a single expression exhibiting the functional relationship between the drag force, Reynolds number (Re), and the pipe-to-sphere diameter ratio (D/d).

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38

Yang, Xiaofeng. "Efficient, second-order in time, and energy stable scheme for a new hydrodynamically coupled three components volume-conserved Allen–Cahn phase-field model." Mathematical Models and Methods in Applied Sciences 31, no. 04 (April 2021): 753–87. http://dx.doi.org/10.1142/s0218202521500184.

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In this paper, we establish a new hydrodynamically coupled phase-field model for three immiscible fluid components system. The model consists of the Navier–Stokes equations and three coupled nonlinear Allen–Cahn type equations, to which we add nonlocal type Lagrange multipliers to conserve the volume of each phase accurately. To solve the model, a linear and energy stable time-marching method is constructed by combining the stabilized-Invariant Energy Quadratization (S-IEQ) approach and the projection method. The well-posedness of the scheme and its unconditional energy stability are rigorously proved. Several numerical simulations in 2D and 3D are carried out, including spinodal decomposition, dynamical deformations of a liquid lens and rising liquid drops, to validate the model and demonstrate the efficiency and energy stability of the proposed scheme, numerically.

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Ng, E. Y. K., and Miao Yi. "Computation of Q3D Viscous Flows in Various Annular Turbine Stages with Heat Transfer." International Journal of Rotating Machinery 4, no. 1 (1998): 25–33. http://dx.doi.org/10.1155/s1023621x98000037.

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A better understanding of the flow inside the multi-stage turbomachines will be very useful to both the designer and operator. The numerical calculation for single blade row has been well established with the time marching computation of the Navier-Stokes equations. But there will exist much more difficulties for the multi-blade rows due to the rotor-stator interaction. The major problems are related to the unsteady flow which will inevitably exist in the blade passages due to the different rotating speed and possible the different in blade number. A method is presented for simulating various turbine blade rows in single-stage environment. A solver has been developed for studying the complex flow analysis of ‘proposed high pressure turbine’ (HPT) using quasi-3-D Reynolds-averaged Navier-Stokes (Q3D RNS) equations. The code achieves good quality solutions quickly even with relatively coarse mesh sizes. The work is first validated both with UTRC's and Zeschky and Gallus' subsonic turbine test cases covering inlet boundary conditions and Reynolds-averaged values. A H-type grid is adopted as it is easy to generate and can readily extend to 3D application. When rows are closely spaced, there can be a strong interaction which will impact the aerodynamic, thermal and structural performance of the blade.

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40

Maiga, Aboubacar Abdoulwahidou. "L’Afrique vue par les écrivains-voyageurs russes (du xive au début du xxe siècle)." Varias, no. 40 (April 5, 2016): 141–57. http://dx.doi.org/10.7202/1035986ar.

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Alors que le xve siècle voit les premiers navires portugais s’aventurer dans les eaux de la côte occidentale de l’Afrique et débarquer sur les îles puis le continent, les marchands et pèlerins russes sont déjà fréquents dans les rues d’Alexandrie et du Caire. Après une longue période de voyages religieux et culturels en Égypte et à la faveur de l’apparition des sociétés géographiques en Europe au début du xixe siècle, de nombreux intellectuels russes pousseront plus loin leur découverte du continent africain. Aujourd’hui, la lecture des témoignages laissés par ces pionniers du voyage en Afrique nous fournit bien des informations sur les premières heures de cette rencontre. Bien que moins nombreux que ceux de leurs collègues de l’Europe de l’Ouest, les récits des voyageurs russes sont d’autant plus importants qu’ils renseignent aussi sur la délicate cohabitation entre religieux européens et africains à Jérusalem. En ce sens, notre démarche s’appuie non seulement sur l’histoire de ces voyages, mais aussi sur une analyse des rapports d’influence qui se jouent entre les écrivains-voyageurs selon les époques.

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41

Colonius, Tim, Sanjiva K. Lele, and Parviz Moin. "The scattering of sound waves by a vortex: numerical simulations and analytical solutions." Journal of Fluid Mechanics 260 (February 10, 1994): 271–98. http://dx.doi.org/10.1017/s0022112094003514.

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The scattering of plane sound waves by a vortex is investigated by solving the compressible Navier–-Stokes equations numerically, and analytically with asymptotic expansions. Numerical errors associated with discretization and boundary conditions are made small by using high-order-accurate spatial differentiation and time marching schemes along with accurate non-reflecting boundary conditions. The accuracy of computations of flow fields with acoustic waves of amplitude five orders of magnitude smaller than the hydrodynamic fluctuations is directly verified. The properties of the scattered field are examined in detail. The results reveal inadequacies in previous vortex scattering theories when the circulation of the vortex is non-zero and refraction by the slowly decaying vortex flow field is important. Approximate analytical solutions that account for the refraction effect are developed and found to be in good agreement with the computations and experiments.

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42

Barnett, M., D. E. Hobbs, and D. E. Edwards. "Inviscid-Viscous Interaction Analysis of Compressor Cascade Performance." Journal of Turbomachinery 113, no. 4 (October 1, 1991): 538–52. http://dx.doi.org/10.1115/1.2929113.

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An inviscid-viscous interaction technique for the analysis of quasi-three-dimensional turbomachinery cascades has been developed. The inviscid flow is calculated using a time-marching, multiple-grid Euler analysis. An inverse, finite-difference viscous-layer analysis, which includes the wake, is employed so that boundary layer separation can be modeled. This analysis has been used to predict the performance of a transonic compressor cascade over the entire incidence range. The results of the numerical investigation in the form of cascade total pressure loss, exit gas angle, and blade pressure distributions are compared with existing experimental data and Navier–Stokes solutions for this cascade, and show that this inviscid-viscous interaction procedure is able to predict cascade loss and airfoil pressure distributions accurately. Several other aspects of the present interaction analysis are examined, including transition and wake modeling, through comparisons with data.

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43

Reddy, D. R., C. J. Steffen, and K. B. M. Q. Zaman. "Computation of Three-Dimensional Compressible Flow From a Rectangular Nozzle With Delta Tabs." Journal of Engineering for Gas Turbines and Power 121, no. 2 (April 1, 1999): 235–42. http://dx.doi.org/10.1115/1.2817111.

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A three-dimensional viscous flow analysis is performed using a time-marching Reynolds-averaged Navier-Stokes code for a 3:1 rectangular nozzle with two delta tabs located at the nozzle exit plane to enhance mixing. Two flow configurations, a subsonic jet case and a supersonic jet case using the same tab configuration, which were previously studied experimentally, are computed and compared with the experimental data. The experimental data include streamwise velocity and vorticity distributions for the subsonic case, and Mach number distributions for the supersonic case, at various axial locations downstream of the nozzle exit. The computational results show very good agreement with the experimental data. In addition, the effect of compressibility on vorticity dynamics is examined by comparing the vorticity contours of the subsonic jet case with those of the supersonic jet case which were not measured in the experiment.

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44

Weber, Stefan, and Max F. Platzer. "A Navier–Stokes Analysis of the Stall Flutter Characteristics of the Buffum Cascade." Journal of Turbomachinery 122, no. 4 (February 1, 2000): 769–76. http://dx.doi.org/10.1115/1.1312800.

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Numerical stall flutter prediction methods are much needed, as modern jet engines require blade designs close to the stability boundaries of the performance map. A Quasi-3D Navier–Stokes code is used to analyze the flow over the oscillating cascade designed and manufactured by Pratt & Whitney, and studied at the NASA Glenn Research Center by Buffum et al. The numerical method solves for the governing equations with a fully implicit time-marching technique in a single passage by making use of a direct-store, periodic boundary condition. For turbulence modeling, the Baldwin–Lomax model is used. To account for transition, the criterion to predict the onset location suggested by Baldwin and Lomax is incorporated. Buffum et al. investigated two incidence cases for three different Mach numbers. The low-incidence case at a Mach number of 0.5 exhibited the formation of small separation bubbles at reduced oscillation frequencies of 0.8 and 1.2. For this case the present approach yielded good agreement with the steady and oscillatory measurements. At high incidence at the same Mach number of 0.5 the measured steady-state pressure distribution and the separation bubble on the upper surface was also found in good agreement with the experiment. But computations for oscillations at high incidence failed to predict the negative damping contribution caused by the leading edge separation. [S0889-504X(00)01304-0]

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45

Liu, Feng, and Xiaoqing Zheng. "A Strongly Coupled Time-Marching Method for Solving the Navier–Stokes andk-ω Turbulence Model Equations with Multigrid." Journal of Computational Physics 128, no. 2 (October 1996): 289–300. http://dx.doi.org/10.1006/jcph.1996.0211.

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46

Bohn, Dieter, Jing Ren, and Michael Sell. "Influence of Stator Clocking on the Unsteady Three-Dimensional Flow in a Two-Stage Turbine." Journal of Turbomachinery 127, no. 1 (January 1, 2005): 156–63. http://dx.doi.org/10.1115/1.1812780.

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To give insight into the influence of the clocking and the stator–rotor interaction, the unsteady three-dimensional (3D) flow through a two-stage turbine is simulated numerically, using a time marching Navier–Stokes computer code with a sliding mesh approach. A stator clocking is applied to the second stator vane over several circumferential positions. The numerical results are compared with the experimental one to check the availability of the code. Clocking effects on the turbine performance, wake trajectories, and outlet flow field are focused. A relative efficiency variation of about 0.52% is concluded among clocking positions. A link between the turbine efficiency and the wake trajectories on the midspan is shown based on the presented clocking analysis in the 3D unsteady flow field. The detailed illustration of the outlet flow field shows that the influence of the clocking at the outlet is focused on the temperature distribution.

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47

Li, Qi, Qing Shan Yang, and Yu Fen Jin. "Numerical Simulation Method for Unsteady Wind Field around Building." Advanced Materials Research 243-249 (May 2011): 521–26. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.521.

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A large eddy simulation algorithm for numerically calculating unsteady wind field around complex geometry building was given. In this algorithm, a curvilinear coordinate system was used to formulate the numerical model, so the complex wind-structure interface could be described precisely. Governing equations were discretized by central differencing schemes with co-located grids. The convection velocity was interpolated by using Rhie-Chow method in order to avoid the inherent odd-even decoupling problem. A common Maker and Cell (MAC) scheme was used to split the velocity-pressure linkage in Navier-Stockes (NS) equation. An explicit Adams-Bashforth differencing scheme was applied for time marching. A corresponding computer code was developed and was validated by performing on simulation of wind field around full-scale Texas Tech University (TTU) building model. Furthermore, the simulation results were compared with corresponding field measure data and wind-tunnel experiment results reported by other authors. The comparison showed that this algorithm is feasible for numerical simulation of unsteady wind field around buildings.

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48

Lee, Jong Hwi, Jong-Hyeon Shin, Se-Myong Chang, and Taegee Min. "Numerical Analysis on Natural Convection Heat Transfer in a Single Circular Fin-Tube Heat Exchanger (Part 1): Numerical Method." Entropy 22, no. 3 (March 21, 2020): 363. http://dx.doi.org/10.3390/e22030363.

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In this research, unsteady three-dimensional incompressible Navier–Stokes equations are solved to simulate experiments with the Boussinesq approximation and validate the proposed numerical model for the design of a circular fin-tube heat exchanger. Unsteady time marching is proposed for a time sweeping analysis of various Rayleigh numbers. The accuracy of the natural convection data of a single horizontal circular tube with the proposed numerical method can be guaranteed when the Rayleigh number based on the tube diameter exceeds 400, which is regarded as the limitation of numerical errors due to instability. Moreover, the effective limit for a circular fin-tube heat exchanger is reached when the Rayleigh number based on the fin gap size ( Ra s ) is equal to or exceeds 100. This is because at low Rayleigh numbers, the air gap between the fins is isolated and rarely affected by natural convection of the outer air, where the fluid provides heat resistance. Thus, the fin acts favorably when Ra s exceeds 100.

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49

Zhuang, Qingyuan, Ronnie Bladh, Erik Munktell, and Yong Lee. "Parametric study on the aeroelastic stability of rotor seals." Journal of the Global Power and Propulsion Society 3 (May 13, 2019): 569–79. http://dx.doi.org/10.33737/jgpps/110751.

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Labyrinth seals are widely used in rotating machinery and can be prone to aeroelastic instabilities. The rapid development of computational fluid dynamics now provides a high-fidelity approach for predicting the aeroelastic behavior of labyrinth seals in three dimension and exhibits great potential within industrial application, especially during the detailed design stages. In the current publication a time-marching unsteady Reynolds-averaged Navier-Stokes solver was employed to study the various historically identified parameters that have essential influence on the stability of labyrinth seals. The findings from the numerical approach agree well with analytical criteria in determining the overall stability of the seal structure while being able to capture the acoustic behavior of the upstream or downstream large cavities and its influence on the inter-fin cavities. The high-fidelity approach provides additional insights on the effects of nodal diameter, travelling wave direction, pressure ratio, and the linearity of the phenomenon for relatively large vibration amplitudes, all of which can aid during the design space exploration.

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LE QUÉRÉ, PATRICK, and MASUD BEHNIA. "From onset of unsteadiness to chaos in a differentially heated square cavity." Journal of Fluid Mechanics 359 (March 25, 1998): 81–107. http://dx.doi.org/10.1017/s0022112097008458.

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We investigate with direct numerical simulations the onset of unsteadiness, the route to chaos and the dynamics of fully chaotic natural convection in an upright square air-filled differentially heated cavity with adiabatic top and bottom walls. The numerical algorithm integrates the Boussinesq-type Navier–Stokes equations in velocity–pressure formulation with a Chebyshev spatial approximation and a finite-difference second-order time-marching scheme. Simulations are performed for Rayleigh numbers up to 1010, which is more than one order of magnitude higher than the onset of unsteadiness. The dynamics of the time-dependent solutions, their time-averaged structure and preliminary results concerning their statistics are presented. In particular, the internal gravity waves are shown to play an important role in the time-dependent dynamics of the solutions, both at the onset of unsteadiness and in the fully chaotic regime. The influence of unsteadiness on the local and global heat transfer coefficients is also examined.

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Journal articles on the topic 'Navire marchand'

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