[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.
[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.
[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.
[17] Brillouin also supervised the translation into French of Boltzmann's textbook on kinetic theory of gases, by Bénard and Alexandre Gallotti.
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.
He defended his dissertation on March 15, 1901, at the age of 26, and was awarded the Docteur ès Sciences physiques, mention très honorable.
[27] Unfortunately, an "excess of modesty" (Bénard's own words[28]) prevented him from showing the results of his work to Lord Kelvin in Glasgow, as well as at the earlier Paris conference.
[29] Kelvin's late brother, James Thomson, had studied thermal convection qualitatively prior to Bénard's work.
Nonetheless, Benard's experimental work in Lyon was the beginning of his contribution to the study of what we now call the Kármán vortex street.
[37] In 1913–1914, Bénard and Dauzère made a series of eight films, on convection and solidification in an evaporating fluid, which were produced with the aid of a large firm, the Gaumont studio.
[44] Bénard was assisted in this work by an ENS student, Pierre-Michel Duffieux, who later (during World War II) founded the field of Fourier optics.
Unfortunately the second award, honoring his invention of polarized binoculars adopted by the French Navy, was annulled due to 'double employment' the next month.
[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.
[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.
[60] The list of the prize committee members makes interesting reading: Appell, Painlevé, Lecornu, Hadamard, Goursat, Lebesgue, and Picard.
[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.
[68] 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.
[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.'
[74] Pierre Chevenard remembers Bénard as "a delightful colleague" and "always happy to render service to young physicists who come to solicit his advice.