Computing fluid structure interaction problem with coupled spectral methods

This paper deals with fluid-structure interactions (FSI), involving a blade profile. An external excitation at a fixed frequency is applied to the structure, and the effect of the fluid on the damping is studied by analyzing Frequency Forced Response (FFR). In order to predict the dynamic behavior of such system, a fully coupled numerical methodology is developed. On the one hand, to compute the time periodic aerodynamic field, a numerical approach the Time Spectral Method (TSM [Sicot (2009)]) or an analytical model (theory of Theodoresen [Theodorsen (1935)]) is used. On the other hand, the Harmonic Balance Method (HBM [Grolet and Thouverez (2012)]) allows the computation of the periodic response for the nonlinear mechanical structure under external/fluid loading. These two spectral approaches will be coupled in order to reach directly the periodic steady state solution

Simulation of near surge instabilities onset in a turbocharger compressor

International audienc

Simulation of near surge instabilities onset in a turbocharger compressor

International audienc

Identification of processes that control the stable isotope composition of rainwater in the humid tropical West-Central Africa

International audienceThis study interprets 11 years (2006 to 2016) and 6 months (March to August in 2017) of respectively monthly and daily isotopic (δD and δ18O) monitoring of rain at Douala (Cameroon), a humid tropical station in Western Africa. The main scope is to analyze the climate controls on precipitation isotopes at different timescales. Firstly, we examine the annual cycles of δ18O. Over the 11 years of survey, the annual cycle exhibits a W shape that is quite reproducible from year to year, with two minima in spring and autumn periods. Based on back trajectory calculations and remote sensing observations of water vapor isotopic composition, we show that the observed depletion in spring and autumn is due to strong convective activity along air mass trajectories. The same effect of convective activity can be observed at the daily timescale. At seasonal and daily time scales, the isotopic composition is also strongly tied to the convective organization and cloud types. More depleted precipitation is associated with larger areas of high clouds