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The study presented in the present paper deals with the modeling of the rotation effects on a homogeneous turbulence evolving without a mean velocity gradient. The developed model results from a modification of the second order model of Haworth and Pope. This modification is expressed as a function of the rotation rate, of the component of the Reynolds tensor and of the characteristic length scale in the direction of the rotation axis. The obtained results have evidenced the great capacity of the present model to describe the rotation effects on the time evolution of the homogeneous decaying turbulence. [ABSTRACT FROM AUTHOR]

Some elements are given on the very multiform career of Antoine Craya. In addition to a strong involvement in applied hydraulics in Grenoble, he was very influential on the research of his colleagues: to give only a few examples of well-known scientists in the Lyon–Grenoble area, he inspired the doctoral work on wall-jets by Jean Mathieu, the doctoral work on channel flow by Geneviève Comte-Bellot, and the dominant research area of René Moreau on magnetohydrodynamic (MHD) turbulence. The main part of this article is devoted to the legacy of Antoine Craya, from his own doctoral dissertation (1957). Inspired by G.I. Taylor probably more than by G. Batchelor, he contributed to establish the concept of HAT (Homogeneous Anisotropic Turbulence), as a useful intermediate step between HIT (Homogeneous Isotropic Turbulence) and fully statistically inhomogeneous turbulent flows. For this purpose, a mean flow with space-uniform velocity gradient can inject energy and anisotropy to a fluctuating flow, and statistical homogeneity is restricted to fluctuations. Complete equations for two-point second-order and three-point third-order velocity correlations were written, both in physical space and in Fourier space, in order to exactly solve mixed pressure–velocity correlations thanks to the incompressibility constraint. Antoine Craya is well known for the use of the eponymous frame of reference, thanks to Jacks Herring (1974). Later recognized as a spectral counterpart of a general decomposition in terms of toroidal/poloidal/dilatational modes, this frame leads to expressing the spectral tensors of correlation with a minimal number of scalar (or pseudo-scalar) descriptors, without loss of information and for arbitrary anisotropy. Craya provided us with a special angle of attack of the so-called RDT (Rapid Distortion Theory) and triadic closures, even if he did not work directly on them. Accordingly, this paper is also an opportunity to come back on the long history of RDT, including the Spectral Linear Theory as a better nomenclature, especially for recent studies. As far as possible, historical milestones are recalled throughout this article, and one recovers the Lagrangian formalism of Cauchy, emphasized by Uriel Frisch as well, with the use of a ‘Cauchy matrix’ in connection with linear theory. Finally, it is shown how the legacy of Craya is present in new (not addressed by him) domains, such as stratified turbulence and MHD turbulence. We discuss how further (past 1957) approaches, by Keith Moffatt (spectral linear theory, 1967), and Steven Orszag (triadic closure for HIT, as EDQNM, Eddy Damped Quasi-Normal Approximation, 1970) can be integrated in a general approach to anisotropic turbulence, which still benefits from Craya's legacy. A synoptic scheme for the description of multipoint statistics is re-discussed on this occasion. More incidentally, connections with Kraichnan theories and with the formalism of Kármán–Howarth–Monin equation(s) are touched upon. [ABSTRACT FROM AUTHOR]

Up until the twentieth century, fluid mechanics was characterised by a strong division between theory and practice. The formulas of mathematicians and physicists were difficult to apply experimentally and their relevance was neither well accepted nor well understood by engineers. In France, where priority was given to the theoretical aspects of this subject, the creation of several centres of fluid mechanics in the 1930s (Lille, Marseille, Paris and Toulouse) represented an attempt at a rapprochement between fluid mechanics, experimental aerodynamics, and hydrodynamics. The aim was to re-establish France's international profile, which had been lost after 1918. In Lille, the leadership of the “Institut de mécanique des fluides” (IMFL) was entrusted to Jospeh Kampé de Fériet, who was able to address questions of both theoretical and experimental nature in the context of his work at the IMFL and at the “Commission de la turbulence atmosphérique”. On the one hand, Kampé de Fériet used a probabilistic approach to give greater mathematical rigour to the statistical theory of turbulence due to Taylor–von Kármán. On the other hand, he played an active part in his group's experimental research on atmospheric turbulence. This paper aims to show in what way Kampé de Fériet's approach to fluid mechanics enabled him to contribute to the international development of the statistical theory of turbulence during the interwar period. [ABSTRACT FROM AUTHOR]

Résumé Cette note présente une méthode mécanique pour la détermination de la porosité totale d'un sol. La méthode présentée consiste à placer un échantillon de sol dans une cellule régulée dont on peut faire varier le volume par paliers grâce à un piston. La porosité du sol se déduit de la variation de la pression totale de la phase gazeuse lors des incréments de volume. La méthode a été validée sur un sol en considérant cinq échantillons de porosités différentes. Les résultats expérimentaux sur la porosité totale sont en bon accord avec les résultats théoriques sur l'ensemble des essais réalisés. This paper presents a mechanical method for the determination of the total porosity of soil. The presented method consists in inserting a sample of soil into a cell that can be regulated by varying the volume of the gas by increments using a piston. The porosity of the soil is deduced from the variation of the total pressure of the gaseous phase during the realization of volume increments. The method has been validated on a soil considering five samples with different porosities. The experimental results on the total porosity are in good agreement with the theoretical results over all tests. [ABSTRACT FROM AUTHOR]