Médaille Henri Bénard physicien scintifique cellules mécanique des fluides ;

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Vendeur: artistic.medal ✉️ (4.941) 100%, Lieu où se trouve: Strasbourg, FR, Lieu de livraison: WORLDWIDE, Numéro de l'objet: 176302991759 Médaille Henri Bénard physicien scintifique cellules mécanique des fluides ;. ________________________________ 253- tir100 Médaille en bronze, France . Frappée vers 1968. Quelques frottements et petits chocs . Graveur / Artiste / Sculpteur :A déterminer  . Dimensions : 66 mm . Poids : 119 g . Métal : bronze . Poinçon sur la tranche (mark on the edge) : triangle + bronze . Envoi rapide et soigné. The stand is not for sale . Le support n'est pas à vendre. _____________________ Henri Claude Bénard (25 October 1874 – 29 March 1939) was a French physicist, best known for his research on convection in liquids that now carries his name, Bénard convection. In addition, the historical surveys of both Tokaty[2] and von Kármán[3] both acknowledge that Bénard studied the vortex shedding phenomenon later named the Kármán vortex street, prior to von Karman's own contributions. Bénard specialized in experimental fluid dynamics, and the use of optical methods to study it. He was a faculty member at the universities at Lyon, Bordeaux, and finally the Sorbonne in Paris.[4] Bénard defended his PhD thesis at the Collège de France on March 15, 1901 entitled "Les Tourbillons cellulaires dans une nappe liquide propageant de la chaleur par convection en régime permanent". Bénard was elected President of the French Society of Physics (SFP) in 1929, following the presidency of Louis Lumière.[5] He was succeeded as President the next year by his friend and former teacher, Jean Perrin. In 1929 Bénard received the Bordin Prize for his work on vortices from the French Academy of Sciences.[6] After his death in 1939, his widow received the Poncelet Prize on his behalf, also from the French Academy of Sciences.[7] A research center of the ERCOFTAC in Lyon is named after him.[8] Life and career Early and student years Henri Bénard was the only son of a small investor, Felix A. Bénard (1851–1884), and his wife Hélène M. Mangeant (1837–1901).[9] He attended elementary school in Lisieux and Caen and high school at the Lycée Louis-le-Grand. In 1894, Bénard was one of 17 students selected from 307 candidates to attend the École normale supérieure (ENS) in the sciences section. His classmates there included Henri Lebesgue and Paul Langevin,[10] and one of his teachers was Jean Perrin.[11] Bénard received his teaching degree in physics in 1897, and then began working as an assistant to Éleuthère Mascart and Marcel Brillouin at the Collège de France in Paris. At this time, Bénard joined the French Society of Physics (SFP).[12] Bénard's initial scientific efforts related to the optical rotation of sugars, resulting in papers co-authored with Mascart[13] and ENS chemistry student L.-J. Simon.[14] The first of these was an experimental measurement of the angle of rotation of polarized light by pure sugar in solution, to determine its concentration for use in saccharimetry, undertaken at the request of the Commission on Sugars and Alcohols, of the Ministry of Finances. Bénard's results were adopted as the legal values in France by the Ministry of Finances.[15] Meanwhile, Marcel Brillouin was teaching a course on the viscosity of liquids and gases, and asked Bénard to repeat Poiseuille's experiments on water flow rates in capillary tubes.[16] However, Brillouin also wanted experiments done with mercury instead of water. Bénard's results (undertaken in the first 6 months of 1899) were summarized in 1907 in Brillouin's textbook based on the course.[17] Brillouin also supervised the translation into French of Boltzmann's textbook on kinetic theory of gases, by Bénard and Alexandre Gallotti.[18] The subject of Bénard's dissertation was cellular thermal convection, inspired by accidental observations made by Adrien Guebhard of convection in a bath of abandoned film developer. Working in Mascart's lab, Bénard carried out the first controlled, systematic scientific experiments on convection in a shallow layer of fluid heated from below.[19] He found that the convective motions organized themselves in semi-regular, semi-permanent cellular patterns. Upflows occurred in the centers of the cells and downflows occurred at their peripheries. There was also a slight depression of the upper free surface of the fluid at each cell center, leading Bénard to speculate about the role of surface tension. He also measured the aspect ratio of the cells and discovered that there was a critical temperature below which no convection occurs. Unfortunately, he attributed this to the solidification of the fluid he was using (spermaceti, a whale oil that is solid at room temperature). Ironically, Bénard would much later become a skeptic about the very concept of the critical temperature difference, although he discovered it.[20][21] In 1900–1901, Bénard presented the results of this work (and the associated optical methods) in four different journals, the Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences,[22] the Revue Générale des Sciences Pures et Appliquées et Bulletin de l'Association Française pour l'Avancement des Sciences,[23] the Journal de Physique Théorique et Appliquée,[24] and the Annales de Chimie et de Physique.[25] He also presented his findings to at least two scientific meetings,[26] as well as in the first thesis of his dissertation. (The second part of his thesis dealt with optical rotation in sugars.) This work laid the foundation for the study of Rayleigh–Bénard convection, the buoyancy-driven flow of fluid Paris In 1922, Bénard moved to the University of Paris, Sorbonne, as senior lecturer in physics. In 1926 he became a full professor, and was teaching introductory physics.[49] In the 1920s he continued his work with the vortex streets, determining an experimental law for the frequency in terms of the velocity of the flow, the viscosity of the fluid, and the size of the obstacle; he claimed that his law contradicted the theoretical results of von Kármán.[50][51][52] In this period, a priority dispute over the discovery of vortex shedding erupted between Bénard and von Kármán, detailed at length by Wesfreid.[53] Meanwhile, Bénard again revisited his work on thermal convection, claiming agreement between his results and the theory of Lord Rayleigh.[54] Bénard led conferences in 1927–1928 at the Sorbonne regarding alternating eddies and cellular eddies.[55] In 1928 Bénard was elected President of the French Society of Physics (SFP), and in that position interacted with a number of important contemporaries such as Louis de Broglie, Paul Langevin, Dimitri Riabouchinsky, and Pierre Weiss.[56] Benard had been an SFP member since 1897. One of Bénard's principal concerns at the SFP was to increase the membership of the society, in particular among engineers and technicians. By the end of his term, he had succeeded in raising the membership from 1222 to 1260: "It is a slow growth, but finally there is growth".[57] In 1929, the French Aeronautics Ministry established an Institute of Fluid Mechanics at the Sorbonne (headed by Henri Villat), and appointed Bénard to be the director of its Fluid Mechanics Laboratory and to the Chair of Experimental Fluid Mechanics.[58] He gave the inaugural address for the laboratory in November.[59] In December, Bénard received the Bordin Prize from the French Academy of Science, in honor of his work on eddies.[60] The list of the prize committee members makes interesting reading: Appell, Painlevé, Lecornu, Hadamard, Goursat, Lebesgue, and Picard. In 1935, Bénard was appointed head of the section on atmospheric convection of the Commission on Atmospheric Turbulence, organized by the French Air Ministry, and headed by Phillipe Wehrlé.[61] Meanwhile, he had already been joined by a number of students: Duson Avsec, Michel Luntz, C. Woronetz, H. Journaud, Victor Volkovisky, Paul Schwarz, V. Romanovsky, and G. Sartory among others.[62] These students studied thermal convection in various regimes, including electroconvection, surface tension-driven convection, etc. Bénard himself returned to the question of convection on the solar photosphere (solar granulation) in 1935.[63] In 1937, Bénard was placed in charge of teaching at the École Supérieure de l'Aéronautique.[64] He and his student Avsec published a major review article of their work on thermal convection in 1938.[65] Finally, on 29 March 1939, at the age of 64, "an unexpected death interrupted his scientific activity".[66] The French Academy of Science awarded its Poncelet Prize that year to his widow, in honor of her late husband.[67] During the second world war, the building lent to Bénard for use as his laboratory was taken over by the German army in 1940.[68] Assessments Bénard's early experimental work on thermal convection has been discussed by Chandrasekhar,[69] Berg, Acrivos, and Boudart,[70] and at great length by Koschmieder.[71] Bénard's later work on convection in shear flows is included in the comprehensive review by R. E. Kelly.[72] Bénard's work on vortex shedding is discussed briefly by Provansal.[73] The astrophysicist Edward A. Spiegel has stated his view that     Bénard and his students soon appreciated that his first experimental results were atypical of ordinary fluids. They went on to attempt 'to define and to measure in a horizontal liquid layer heated from below, the convection currents that prevail, considered as near as possible to their state of greatest stability.' The problem so formulated is at the center of modern convective pattern research, and the work of Bénard's students anticipated some important modern discoveries and methods. Surprisingly, their early grasp of the basic issues is generally overlooked in the current literature.[74] Pierre Chevenard remembers Bénard as "a delightful colleague" and "always happy to render service to young physicists who come to solicit his advice."[75] Bénard was also said to be modest to a fault, as he "disliked publishing and never presented a synthesis of his views."[76] See also     Scientific phenomena named after people Further reading     David Aubin (2008). The memory of life itself: Bénard's cells and the cinematography of self-organization. Studies in History and Philosophy of Science vol. 39, pp. 359–369.     Henri Bénard. (1926 and 1929). Notice sur les Titres et Travaux Scientifiques de M. Henri Bénard (Gauthier-Villars, Paris).     Francois Charru (2023). Fluid mechanics in France in the first half of the twentieth century. Annual Review of FlHenri Bénard, né le 25 octobre 1874 à Lieurey et mort le 29 mars 1939 à Neuilly-sur-Seine)1, est un physicien français. Il est à l'origine, dès 1900, de l'observation des cellules de Bénard2. Carrière Henri Bénard a soutenu sa thèse de doctorat, intitulée Les Tourbillons cellulaires dans une nappe liquide propageant de la chaleur par convection en régime permanent, le 15 mars 1901 au Collège de France3. De 1922 (succédant à Paul Janet) à 1929 (remplacé par Marcel Pauthenier), il est maître d
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