CEA Valduc, France
During the welding of tantalum with a ND: YAG pulsed laser, a deep and narrow cavity, called the keyhole, is formed. At the end of the process, surface tension forces provoke the collapse of the keyhole. For important interface deformations, gas bubbles can be trapped into the melting pool. If the solidification time is insufficient, these bubbles give birth to residual porosities. The aim of the ...
O. Richter, F. Suhling, and S. Moenickes
Technische Universität Braunschweig, Germany
The spatial dynamics of the invasion of new species and genetic dispersal is studied under the presumption of rising temperature by using a coherent approach of coupled partial differential equations of the reaction diffusion type. The nonlinear reaction terms model the population dynamics, genetic exchange and competition. Temperature reaction norms of reproduction rates are conferred by a two ...
Two-Dimensional FEM Analysis Of Brillouin Gain Spectra In Acoustic Guiding And Acoustic Antiguiding Single Mode Optical Fibers
Y.S. Mamdem, X. Pheron, F.Taillade, Y. Jaouën, R. Gabet, V. Lanticq[1,3], G. Moreau, A. Boukenter, Y. Ouerdane, S. Lesoille, and J. Bertrand
EDF R&D, Chatou, France
ANDRA, Chatenay-Malabry, France
LCPC, Paris, France
Telecom ParisTech, Paris, France
Laboratoire Hubert Curien, Saint-Etienne, France
We present a full modal -analysis of optical and acoustic properties based on two-dimensional finite-element method (2D-FEM) for Brillouin Gain spectrum (BGS) determination in optical fibers with COMSOL. This model enables us to predict precisely the BGS of any kind of silica fiber knowing well the geometry of doping composition. The results of numerical modeling have shown good agreement in ...
F. Grilli, F. Sirois, and R. Brambilla
Karlsruhe Institute of Technology, Karlsruhe, Germany
Ecole Polytechnique de Montréal, Montréal, Canada
ERSE SpA, Milan, Italy
Second-generation high-temperature superconducting (HTS) tapes are very promising superconductors for ac applications and numerical models are very important for predicting their performance, e.g. for computing the ac losses. These tapes are characterized by a very large aspect ratio: the width of the superconducting film is typically between 4 and 12 mm, whereas its thickness is in the ...
Modelling of Transport Phenomena and Effect of Applied Electrical Field on Heavy Metals Recovery during Application of the Electro-remediation Process
A. Mahmoud, and J. Beaugrand
Laboratoire de Thermique Energétique et Procédés, ENSGTI, Pau, France
A mathematical model for the simulation of contaminant such as heavy metals removal from soils by electric fields was performed in a 2-D geometry using COMSOL Multiphysics. Electrokinetic phenomena is the result of the coupling between hydraulic and electrical potential gradients in fine grained soils. The model describes the coupled transport of mass and charge of species subjected to an ...
Homogeneous and Inhomogeneous Model for Flow and Heat Transfer in Porous Materials as High Temperature Solar Air Receivers
O. Smirnova, T. Fend, P. Schwaryboezl, and D. Schoellgen
German Aerospace Center, Institute of Technical Thermodynamics, Koeln, Germany
Results of simulations on flow and heat transfer in a porous Silicon Carbide honeycomb structure applied as a solar air receiver are presented. In this application porous materials are put in concentrated solar radiation. Flux densities of up to 1000 MW/m² are reached. Simultanously, ambient air flows through the material to be heated up to temperatures of app. 800°C. This hot air is then used ...
A.T. Vermeltfoort, and J. van Schijndel
Eindhoven University of Technology, the Netherlands
The tensile strength of masonry is relatively low compared to its compressive strength and is affected by the direction of the joints and their filling. In masonry with modern thin layer mortar (joint thickness 3 to 5 mm) sometimes the head joints are left open. A total of 13 model-walls was built and for each model four general purpose mortar combinations and three thin layer mortar combinations ...
University of Napoli Federico II, Naples, Italy
This paper presents some results of numerical simulations carried out to investigate the basic hydrodynamic interactions between the laminar flow in the water column above triangular bedforms and the Darcian flow in the underlying permeable sediments. The flow was described by the Navier-Stokes equation in the free region and the Darcy equation in the porous region. Numerical simulations were ...
G. Maizza, R. Cagliero, and A. Santoro
Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino, Torino, Italy
Powder metallurgy is a key technology for manufacturing advanced components based on TiAl alloys. Cold compaction is the primary step to produce green parts. Cold deformation of TiAl powder is difficult due to its typical poor ductility. Plastic deformation and cracking susceptibility of TiAl powder strongly depends on micro-mechanical phenomena. To manage real compaction problems more reliable ...
Using Computational Fluid Dynamics Model to Predict Changes in Velocity properties in Stented Carotid Artery
S. Vaidehi, and A. Ritter
Stevens Institute of Technolgy, Hoboken, NJ, USA
Atherosclerosis is a disease that narrows, thickens, hardens and restructures a blood vessel due to substantial plaque deposit. In the Carotid Artery, the decision to treat using endarterectomy and stenting is determined by the velocity as measured by Doppler flow in the common Carotid Artery. The measured Doppler velocity as compared with the contra-lateral side has been correlated with the ...