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Stent placement is the only available treatment in patients presenting either a localized external compression or a malacia of the tracheobronchial tree. To assess the functional benefit of prosthesis insertion [...]

In unresectable non-small cell lung cancer (NSCLC) with a patent mainstem bronchus, some studies of obstructive tumors, showed (1) a poor role for irradiation in obtaining efficient debulking and (2) [...]

Jean-Michel Vergnon, M.D.; Jean-Claude Barthelemy, M.D.; Jeanne Riffat, M.D.; Christian Boissier, M.D.; Alain Claudy, M.D.; and Andre Emonot, M.D. Vasospasm of RP is thought to occur in the lungs. To [...]

We will try to present herein the main issues of our investigation in numerical methods for two-phase flow modeling, within the framework of the NEPTUNE project, which benefits from both contributions of CEA and EDF. These may be recast in five work packages. The first two are devoted to the mathematical and numerical modeling of two-phase flows with interfaces and the two-fluid two pressure approach. This in particular includes investigation of relaxation methods in order to establish correct links with standard two-fluid models, which are the core of the third work package. Computations of the interaction of shock waves with bubbles will be presented. Some new results concerning two-fluid and three-field flow modeling will also be briefly presented. Part of the work in the third work package concerns benchmarking, and comparison with several hyperbolic solvers, but also improvement of numerical treatment of source terms, multi-field models and suitable boundary conditions. The fourth one, which deals with the interfacial coupling of codes, is probably the most important one since it requires connecting all models together. Since little attention has been paid to this crucial point, part of the focus will be given in this paper on the coupling of equations of state, one-dimensional and three-dimensional codes, porous approach and free medium approach, but also on ongoing work concerning relaxed and unrelaxed hyperbolic two-phase flow models. The fifth work package gathers all classical contributions in numerical methods, including: recent applications of fictitious domain methods ; preconditioning of so-called “low Mach number” two-phase flows (with applications to the motion of rising bubbles in water) ; parallel and multigrid techniques (with applications to steam generators in nuclear power plants) ; Finite Volume Element methods (with applications to the standard two-fluid models) ; construction and validation of new exact or approximate Riemann solvers (in order to cope with vanishing phases). The latter five obviously aim at improving accuracy, stability and also at reducing CPU time. A few examples will enable to highlight the main advantages and possible drawbacks of these new developments, and the impact of the current and future increasing computational facilities.

AbstractThe WATLON water experiment about fluid mixing in a tee pipe is calculated with a finite element volume method and a large eddy simulation (LES) approach, with the TRIO-U code. Its unstructured tetrahedron grids do not lead to the same noteworthy disagreements previously mentioned with Cartesian grids. Branch and main pipe inlet velocity fluctuations due to turbulence are simulated with the use of “periodic boxes.” These more realistic inlet fluctuations allow physical instabilities to develop, improving the predictions. When an elbow is added upstream of the injection, the influence of the secondary flow on temperature-averaged values and fluctuations is underlined.

Forecasting pollination would help allergists to establish an appropriate prevention for allergic patients. Previous studies have related meteorological variables to airborne pollen counts; patients suffer allergy episodes before the peak of pollen is reached. A 10-year study was done in Saint-Etienne (France) by a multi-disciplinary team (medical doctors, meteorologists, plant biologists). The frequency distribution of patients with pollinosis was obtained from mid-January to August every year. The meteorological station recorded the temperatures daily; pollen counts were obtained with a pollen trap. The maturation stages of trees (ash, birch) and graminaceae (dactyl and meadow grass) were followed by weekly sampling and provided the exact date of pollination. Mathematical models were built to predict the developmental stages of plant growth and the values were compared with the exact dates obtained every year. The frequency distribution of allergic patients was either mono or biphasic according to the evolution of daily temperatures. The maximum peak of patients always preceded the peak of graminaceae over the 10-year period. Different models were found to adequately predict the pollination dates: a Q10-based algorithm best described the pollination date of trees; a weighted Q10algorithm best reflected the pollination of graminaceae.

This article presents the guiding principles of the architecture of Trio_U, a new generation of software for thermohydraulic calculations. Trio_U is designed to serve as a thermohydraulic development platform. Its basic conception is object-oriented and it is written in C++. The article demonstrates how this type of design enables an open, modular software architecture.