Numerical and experimental investigations of three-dimensional container filling with Newtonian viscous fluids

This work employs numerical and experimental approaches to investigate three-dimensional container filling with Newtonian viscous fluids. For this purpose, a computer code developed for simulating three-dimensional free surface flows has been used. The CFD Freeflow3D code was specifically designed to deal with unsteady three-dimensional flows possessing multiple moving free surfaces. An experimental apparatus that allows the visualization of the various phenomena that can occur during the filling of containers has been constructed and employed. Experiments on container filling were carried out by varying the fluid velocity at the injection nozzle. This paper presents a computational study on container filling with Newtonian viscous fluids and employs the experimental results to validate the software. The experimental observations were compared with the predictions from the Freeflow3D code and good agreement between the two sets of results is observed. Moreover, the code predictions showed that it is capable of capturing the most relevant phenomena observed in the experiments.The Brazilian authors would like to acknowledge the financial support given by the funding agencies: CNPq - Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (Grant Nos. 302631/2010-0, 301408/2009-2, 472514/2011-3), FAPESP - Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (Grant No. 2011/13930-0) and CAPES Grant Nos. BEX 2844/10-9 and 226/09 (CAPES-FCT). This work is part of the activities developed within the CEPID-CeMEAI FAPESP project Grant No. 2013/07375 - 0 and also benefits from the early collaboration within the framework of the University of Sao Paulo (Brazil) and University of Porto (Portugal) research agreements. The Portuguese authors gratefully acknowledge funding from Fundacao para a Ciencia e Tecnologia (FCT) under the project PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25-2013-2014), project PTDC/MAT/121185/2010 and FEDER, via FCT

Strong temporal and spatial variation of dissolved Cu isotope composition in acid mine drainage under contrasted hydrological conditions

Copper export and mobility in acid mine drainage are difficult to understand with conventional approaches. Within this context, Cu isotopes could be a powerful tool and here we have examined the relative abundance of dissolved (0.22 μm) and bed sediments samples. Our goals were to 1) assess Cu sources variability at the upstream point under contrasted hydrological conditions and 2) investigate the conservative vs. non conservative Cu behavior along a stream. Average δ65Cu values varied from -0.47 to -0.08‰ (n = 9) upstream and from -0.63 to -0.31‰ downstream (n = 7) demonstrating that Cu isotopes are heterogeneous over the diel cycle and along the Meca River. During dry conditions, at the upstream point of the Meca River the Cu isotopic composition was heavier which is in agreement with the preferential release of heavy isotopes during the oxidative dissolution of primary sulfides. The more negative values obtained during high water flow are explained by the contribution of soil and waste deposit weathering. Finally, a comparison of upstream vs. downstream Cu isotope composition is consistent with a conservative behavior of Cu, and isotope mass balance calculations estimate that 87% of dissolved Cu detected downstream originate from the Tharsis mine outlet. These interpretations were supported by thermodynamic modelling and sediment characterization data (X-ray diffraction, Raman Spectroscopy). Overall, based on contrasted hydrological conditions (dry vs flooded), and taking the advantage of isotope insensitivity to dilution, the present work demonstrates the efficiency of using the Cu isotopes approach for tracing sources and processes in the AMD regions

A Merchant Mechanism for Electricity Transmission Expansion

We propose a merchant mechanism to expand electricity transmission based on long-term financial transmission rights (FTRs). Due to network loop flows, a change in network capacity might imply negative externalities on existing transmission property rights. The system operator thus needs a protocol for awarding incremental FTRs that maximize investors’ preferences, and preserves certain currently unallocated FTRs (or proxy awards) so as to maintain revenue adequacy. In this paper we define a proxy award as the best use of the current network along the same direction as the incremental awards. We then develop a bi-level programming model for allocation of long-term FTRs according to this rule and apply it to different network topologies. We find that simultaneous feasibility for a transmission expansion project crucially depends on the investor-preference and the proxy-preference parameters. Likewise, for a given amount of pre-existing FTRs the larger the current capacity the greater the need to reserve some FTRs for possible negative externalities generated by the expansion changes. Copyright Springer Science+Business Media, Inc. 2006Electricity transmission, Financial transmission rights, Merchant transmission expansion, Bi-level programming, Power flow model, L51, L91, L94, Q40,

Toward a combined merchant-regulatory mechanism for electricity transmission expansion

Electricity transmission, Financial transmission rights, Incentive regulation, Loop-flow problem, D24, L51, L94,