3D Numerical modelling of multistrands inductors

International audienc

3-D Multistrands Inductor Modeling: Influence of Complex Geometrical Arrangements

International audienceWe study multistrands inductors in the context of high-frequency induction processes. They present the advantage of reducing Joule losses compared with solid inductors. We remind why that type of cable seems to be promising and what electromagnetic effects are already identified. We have to understand precisely what happens inside the inductor. Numerical simulation of the electromagnetic behavior of these objects is complicated due to the complexity of their 3-D geometry and to the size of the generated numerical system. We have developed a 3-D electromagnetic software based on an integral methods using classical Biot and Savart law. We applied this model for the simulation of multistrands cables with helical arrangement of strands. Execution time is reduced by the parallelization of the system building and the solver. We present some results obtained with 3-D simulations using integral methods for different configurations

Ecotoxicity of uranium to Tubifex tubifex worms (Annelida, Clitellata, Tubificidae) exposed to contaminated sediment

In freshwater ecosystems, sediments act as an accumulation compartment for metallic pollutants as uranium. However, they are also the habitats of numerous benthic macroinvertebrates that directly influence the structure and functioning of such environments. Consequently, these organisms could be affected by uranium. This laboratory study aimed to assess the ecotoxicity of uranium on Tubifex tubifex through 12-day exposure to contaminated sediment (0-5980 μg U g-1 dry wt). At high concentrations (>599 μg U g-1 dry wt), malformations were observed, and survival, biomass and burrowing activity were all reduced. This relative high resistance in polluted environments can be explained mainly by the implementation of several processes as autotomy, regeneration ability, increased production of mucus, a hormetic effect on biomass and a probable strategy for avoiding the contaminated sediment. This study represents the first assessment of uranium impact on T. tubifex at realistic concentrations in sediments near mining sites. © 2008 Elsevier Inc. All rights reserved

Electromagnetic modeling with 3D integral method

International audienceThe present work focus on numerical modeling of electromagnetic phenomenon in the inductive processes. Our objective is to be able to model 3D configurations, taking into account high number of objects, small space between active elements of the installation and multi-scale. To achieve this goal we develop an integral method with parallel computing. The obtained results show the efficiency of this approach

Thermoelectric problem for an axisymmetric ellipsoid particle in the liquid metal: Analytical solution and numerical modeling

International audienceA thermo-electric problem is solved analytically for an electrically conducting particle in a form of an ellipsoid of revolution immersed in the liquid metal and subjected to a temperature gradient. It is shown that the density of the thermoelectric current is constant inside the particle and its value depends on the eccentricity of the ellipse in the meridian plane of the ellipsoid, but does not depend on the size of the particle. Another parameter which affects the value of the thermoelectric current is the orientation of the ellipsoid with respect to the imposed temperature gradient. The vector of the thermoelectric current inside the particle and the vector of the imposed thermal gradient are co-planar, but a planar angle between these vectors exist and its value is also a function of the eccentricity of the ellipse and its orientation in a thermal field. Limiting minimal and maximal value of the thermoelectric current inside a very elongated particle are found and compared with values obtained in simulations for a dendrite grain. Numerical simulation performed with FEM software for two orientations of an elongated ellipsoid with respect to the imposed thermal gradient provided results similar to analytical solutions with the relative error less than 0.1%