Turbulence model and numerical scheme assessment for buffet computations

International audienceThe prediction of shock-induced oscillations over transonic rigid airfoils is important for a better understanding of the buffeting phenomenon. The unsteady resolution of the Navier-Stokes equations is performed with various transport-equation turbulence models in which corrections are added for nonequilibrium flows. The lack of numerical efficiency due to the CFL stability condition is circumvented by the use of a wall law approach and a dual time stepping method. Moreover, various numerical schemes are used to try and be independent of the numerical discretization. Comparisons are made with the experimental results obtained for the supercritical RA16SC1 airfoil. They show the interest in using the SST correction or realizability conditions to get correct predictions of the frequency, amplitude and pressure fluctuations over the airfoil

Numerical simulations of a transport-aircraft configuration

International audienceAn implicit low-cost Navier-Stokes solver combined with a multigrid algorithm and wall functions has been developed for efficient numerical simulations on a realistic wing-body aircraft configuration. A study of the behavior of different transport-equation turbulence models is given. Comparisons are made with experimental data. The structure of the three-dimensional flow separation predicted by computations is described and its topological coherence is checked

Using numerical plant models and phenotypic correlation space to design achievable ideotypes

Numerical plant models can predict the outcome of plant traits modifications resulting from genetic variations, on plant performance, by simulating physiological processes and their interaction with the environment. Optimization methods complement those models to design ideotypes, i.e. ideal values of a set of plant traits resulting in optimal adaptation for given combinations of environment and management, mainly through the maximization of a performance criteria (e.g. yield, light interception). As use of simulation models gains momentum in plant breeding, numerical experiments must be carefully engineered to provide accurate and attainable results, rooting them in biological reality. Here, we propose a multi-objective optimization formulation that includes a metric of performance, returned by the numerical model, and a metric of feasibility, accounting for correlations between traits based on field observations. We applied this approach to two contrasting models: a process-based crop model of sunflower and a functional-structural plant model of apple trees. In both cases, the method successfully characterized key plant traits and identified a continuum of optimal solutions, ranging from the most feasible to the most efficient. The present study thus provides successful proof of concept for this enhanced modeling approach, which identified paths for desirable trait modification, including direction and intensity.Comment: 25 pages, 5 figures, 2017, Plant, Cell and Environmen

Que signifie, comment traduire en portugais l'expression idiomatique "couper l'herbe sous le pied à quelqu'un"?

Ce travail émane du projet de recherche, coordonné par Robert Ponge à l'UFRGS (Brésil), qui porte sur les difficultés de compréhension et/ou de traduction (abréviation: DCT) du FLE en portugais du Brésil dont les deux objectifs sont l’objectif théorico-descriptif (l’élaboration d’une classification des types de difficultés) et l’objectif pratique (l'organisation d'un glossaire réunissant une quantité de difficultés concrètes). Sa méthodologie est bibliographique. Pour définir la traduction, nous adoptons DUBOIS (p.486), revu par PONGE à partir de SOBRAL. Les autres fondements théoriques sont les études sur les DCT (MOUNIN; RÓNAI, 1976a, 1976b; PORTINHO; PONGE), les études sur les expressions (ou locutions) idiomatiques (DUBOIS; REY; TLFi; SILVA). Pourquoi les expressions idiomatiques? Parce que c’est le type spécifique de difficulté que nous examinons ici: nous nous penchons sur les DCT posées par la locution «couper l’herbe sous le pied à quelqu’un», trouvée dans Melmoth réconcilié, récit d’Honoré de Balzac (1835), que nous travaillons à traduire en portugais du Brésil. Quel chemin avons-nous pris? D’abord une rapide présentation de notre projet de recherche (PONGE) et une brève caractérisation théorique des locutions, ce qui permet de comprendre pourquoi elles peuvent occasionner des DCT. Nous présentons alors le processus de recherches lexico-sémantiques suivi, les solutions envisagées et celle finalement adoptée pour traduire la locution examinée.Fil: Jardim Da Silva, Gabriela.Fil: Ponge, Robert

Meth­yl(phen­yl)phosphinic acid

The crystal structure of the title compound, C7H9O2P, displays O—H⋯O hydrogen bonding , which links individual mol­ecules related via the c-glide plane and translational symmetry along the crystallographic b-axis direction into continuous chains