A Very High-Order Accurate Staggered Finite Volume Scheme for the Stationary Incompressible Navier–Stokes and Euler Equations on Unstructured Meshes

International audienceWe propose a sixth-order staggered finite volume scheme based on polynomial reconstructions to achieve high accurate numerical solutions for the incompressible Navier-Stokes and Euler equations. The scheme is equipped with a fixed-point algorithm with solution relaxation to speed-up the convergence and reduce the computation time. Numerical tests are provided to assess the effectiveness of the method to achieve up to sixth-order con-2 Ricardo Costa et al. vergence rates. Simulations for the benchmark lid-driven cavity problem are also provided to highlight the benefit of the proposed high-order scheme

'Pro Patria' - Le bon evêque de Meaux

The bishop of Meaux with nurses and a member of the clergy, welcoming some wounded soldiers.Translation of title: For the country. The good bishop of Meaux.Lower left corner: Cette estampe est la premère d'une série intitulée 'Pro Patria' qui paraîtra durant la guerre.Signed: P. Loubere, 1914.Promotional goal: Fr. J5. 1914.Item is no. 165 in a printed checklist available in the Library of Congress Prints and Photographs Reading Room

A second-order accurate material-order-independent interface reconstruction technique for multi-material flow simulations

International audienc

Validation of the Peritraumatic Dissociative Experiences Questionnaire and Peritraumatic Distress Inventory in school-aged victims of road traffic accidents

International audienc

Modeling of laser–plasma interaction on hydrodynamic scales: Physics development and comparison with experiments

International audienceThe forthcoming laser installations related to inertial confinement fusion, Laser Mégajoule (LMJ) (France) and National Ignition Facility (NIF) (USA), require multidimensional numerical simulation tools for interpreting current experimental data and to perform predictive modeling for future experiments. Simulations of macroscopic plasma volumes of the order of 1 mm^3 and laser exposure times of the order of hundreds of picoseconds are necessary. We present recent developments in the PARAX code towards this goal. The laser field is treated in a standard paraxial approximation in three dimensions. The plasma response is described by single-fluid, two-temperature, fully nonlinear hydrodynamical equations in the plane transverse to the laser propagation axis. The code also accounts for the dominant nonlocal transport terms in spectral form originating from a linearized solution to the Fokker–Planck equation. The simulations of interest are hohlraum plasmas in the case of indirect drive or the plasma corona for direct drive. Recent experimental results on plasma-induced smoothing of RPP laser beams are used to validate the code

A leader in an emerging new international market: the determinants of French wine exports, 1848–1938

The objective of this article is to provide an in-depth study of France''s performance in the new international wine market that began to take shape from the middle of the nineteenth century. We analyse the main determinants of its success in exporting ordinary and high-quality wine using a gravity model for both types of wine. The article shows how France lost foreign markets in the ordinary wine sector, due to difficulties in maintaining its exports, which resulted from the decrease in production caused by the phylloxera plague and increasing competition from growing numbers of producers who were more efficient at producing these types of wines. However, in the high-quality wine market, French exporters enjoyed considerable success, increasing their exports thanks to their efforts to offer a product that was highly valued abroad and the use of modern marketing and sales techniques. The exports benefited from the fall in transport costs and French colonial expansion. However, exports of both products were severely affected by a series of major events, including the First World War, the Russian Revolution, Prohibition in the US, and the Great Depression. This case study of the wine market shows that the collapse of the first globalization was not the same for all products

A Priori Neural Networks Versus A Posteriori MOOD Loop: A High Accurate 1D FV Scheme Testing Bed

In this work we present an attempt to replace an a posteriori MOOD loop used in a high accurate Finite Volume (FV) scheme by a trained artificial Neural Network (NN). The MOOD loop, by decrementing the reconstruction polynomial degrees, ensures accuracy, essentially non-oscillatory, robustness properties and preserves physical features. Indeed it replaces the classical a priori limiting strategy by an a posteriori troubled cell detection, supplemented with a local time-step re-computation using a lower order FV scheme (ie lower polynomial degree reconstructions). We have trained shallow NNs made of only two so-called hidden layers and few perceptrons which a priori produces an educated guess (classification) of the appropriate polynomial degree to be used in a given cell knowing the physical and numerical states in its vicinity. We present a proof of concept in 1D. The strategy to train and use such NNs is described on several 1D toy models: scalar advection and Burgers' equation, the isentropic Euler and radiative M1 systems. Each toy model brings new difficulties which are enlightened on the obtained numerical solutions. On these toy models, and for the proposed test cases, we observe that an artificial NN can be trained and substituted to the a posteriori MOOD loop in mimicking the numerical admissibility criteria and predicting the appropriate polynomial degree to be employed safely. The physical admissibility criteria is however still dealt with the a posteriori MOOD loop. Constructing a valid training data set is of paramount importance, but once available, the numerical scheme supplemented with NN produces promising results in this 1D setting. Keywords Neural network • Machine learning • Finite Volume scheme • High accuracy • Hyperbolic system • a posteriori MOOD. Mathematics Subject Classification (2010) 65M08 • 65A04 • 65Z05 • 85A2