Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries

The influence of a small relative density difference on the displacement of two miscible liquids is studied experimentally in transparent 2D networks of micro channels. Both stable displacements in which the denser fluid enters at the bottom of the cell and displaces the lighter one and unstable displacements in which the lighter fluid is injected at the bottom and displaces the denser one are realized. Except at the lowest mean flow velocity U, the average $C(x,t)$ of the relative concentration satisfies a convection-dispersion equation. The dispersion coefficient is studied as function of the relative magnitude of fluid velocity and of the velocity of buoyancy driven fluid motion. A model is suggested and its applicability to previous results obtained in 3D media is discussed

Real-time analysis of polymer flow under real processing conditions applied to microinjection molding

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Genetic Analysis of Avian Influenza Virus from Wild Birds and Mallards Reared for Shooting in Denmark

This paper reports complementary experimental and theoretical investigations focussed on the laser milling of theamorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5, also known as Vitreloy 1, in ambient air, using 220 ns pulses. Theconducted experiments showed that the formation of crystalline precipitates required a relatively large overlapbetween pulses when machining with a fluence of 6 J/cm2 and a pulse repetition frequency of 250 KHz. The loss ofthe fully amorphous nature of this material could also be achieved for a substantially smaller pulse overlap andfrequency. In this case, the lower thermal load associated with the reduction in the value of these parameters wasbalanced by increasing the delivered fluence by one order of magnitude, i.e. 70 J/cm2. Using theoretical temperatureprofiles associated with the considered laser milling operations, it was suggested that different crystallisationphenomena could be at play between both levels of fluence values utilised

Overview of the system alone and system/CFD coupled calculations of the PHENIX Natural Circulation Test within the THINS project

International audienceThe PHENIX sodium cooled fast reactor started operation in 1973 and was shut down in 2009. Before decommissioning, an ultimate test program was designed and performed to provide valuable data for the development of future sodium cooled fast reactors, as the so-called Astrid prototype in France. Among these ultimate tests, a thermal-hydraulic Natural Convection Test (NCT) was set-up in June 2009. Starting from a reduced power state of 120 MWt, the NCT consists of a loss of the heat sink combined with a reactor scram and a primary pumps trip leading to stabilized natural circulation in the primary sodium system. The thermal-hydraulics innovative system project (THINS project), sponsored by the European Community in the frame of the 7th FP has selected this transient for validation of both stand-alone system code simulations and coupled simulations using system and CFD codes. Participants from three organizations (CEA, IRSN and KIT) have addressed this transient using different system codes (CATHARE, DYN2B and ATHLET) and CFD codes (TRIO-U and OPEN FOAM). The present paper depicts the different modeling approaches, methodologies and compares the numerical results with the available experimental data. Finally, the main lessons learned from the work performed within the THINS project on the PHENIX NCT with respect to code development and validation are summarized. © 2014 Elsevier B.V. All rights reserved

International benchmark on the natural convection test in Phenix reactor

The French Phenix sodium cooled fast reactor (SFR) started operation in 1973 and was stopped in 2009. Before the reactor was definitively shutdown, several final tests were planned and performed, including a natural convection test in the primary circuit. During this natural convection test, the heat rejection provided by the steam generators was disabled, followed several minutes later by reactor scram and coast-down of the primary pumps. The International Atomic Energy Agency (IAEA) launched a Coordinated Research Project (CRP) named "control rod withdrawal and sodium natural circulation tests performed during the Phenix end-of-life experiments". The overall purpose of the CRP was to improve the Member States' analytical capabilities in the field of SFR safety. An international benchmark on the natural convection test was organized with "blind" calculations in a first step, then "post-test" calculations and sensitivity studies compared with reactor measurements. Eight organizations from seven Member States took part in the benchmark: ANL (USA), CEA (France), IGCAR (India), IPPE (Russian Federation), IRSN (France), KAERI (Korea), PSI (Switzerland) and University of Fukui (Japan). Each organization performed computations and contributed to the analysis and global recommendations. This paper summarizes the findings of the CRP benchmark exercise associated with the Phenix natural convection test, including blind calculations, post-test calculations and comparisons with measured data. General comments and recommendations are pointed out to improve future simulations of natural convection in SFRs. © 2013 Elsevier B.V