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461.
Florian Perez Claude Mügler Philippe Jean-Baptiste Jean Luc Charlou 《Computational Geosciences》2013,17(2):217-237
We present a new numerical tool developed in the Cast3M software framework to model hydrothermal circulation. Thermodynamic properties of one-phase pure water are calculated from the International Association for the Properties of Water and Steam formulation. This new numerical tool is validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also give results in good agreement with already published simulations. This new numerical tool is used to construct a geometric and physical conceptual model of the Rainbow vent site at 36°14′N on the Mid-Atlantic Ridge. Several configurations are discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modeled with hydrothermal circulation in a homogeneous-permeability porous medium. These high values require the presence of a fault or a preferential pathway right below the venting site. We propose and discuss a two-dimensional single-pass model that allows us to simulate both high temperatures and high mass fluxes. This modeling of the hydrothermal circulation at the Rainbow site constitutes the first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field. 相似文献
462.
Héloïse Michaud Yann Leredde Claude Estournel Éric Berthebaud Patrick Marsaleix 《Comptes Rendus Geoscience》2013,345(9-10):361-372
While oceanic circulation in the Gulf of Lion (GoL) has often been studied in calm weather or with northerly winds (Tramontane or Mistral) through observations and numerical circulation models, few studies have focused on southeasterly storm events. Yet, correct representation of the circulation during storms is crucial if the suspension of sediments is to be correctly modelled throughout the Gulf. The purpose of this paper is to describe the hydrodynamics in the Gulf of Aigues-Mortes (NW of the GoL) during the storm of 18 February 2007 by using a set of data from an ADCP station placed at a depth of 65 m on the sea bed off the coast at Sète, supplemented by the ocean circulation model SYMPHONIE. This storm was characterized by a moderate south-easterly wind (15 m . s?1) and waves of up to 5 m of significant height at its apex. At the ADCP, strong currents of up to 0.8 m . s?1 near the surface and 0.5 m . s?1 near the bottom were recorded, parallel to the coast, flowing towards the south-west. The simulated currents were widely underestimated, even taking the effect of waves into account in the model. It was suspected that the representation of the wind in the atmospheric model was an underestimation. A new simulation was therefore run with an arbitrarily chosen stronger wind and its results were in much better agreement with the measurements. A simplified theoretical analysis successfully isolated the wind-induced processes, responsible for the strong currents measured during the apex and the strong vertical shear that occurred at the beginning of the storm. These processes were: 1/ the barotropic geostrophic current induced by a wind parallel to the coast and 2/ the Ekman spiral. The duration of the storm (about 36 h at the apex) explains the continuous increase of the current as predicted by the theory. The frictionally induced Ekman transport explains the current shear in the surface layer in the rising stage of the storm, and the addition of high waves and strong wind at the apex is more in favour of strong vertical mixing in the surface layer. 相似文献
463.
Naoual Gamrani Khalid R’kha Chaham Mouncif Ibnoussina Fabio Fratini Luisa Rovero Ugo Tonietti Mohammed Mansori Lehcen Daoudi Claude Favotto Nasrrddine Youbi 《Environmental Earth Sciences》2012,66(1):129-140
This work focuses on the building material used in the Saadian sugar refinery of Chichaoua (about 70 km southwest of Marrakesh).
The study involved a classification of different types of rammed earth, followed by their mineralogical characterization based
on optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). These studies are complemented by chemical
investigations, X-ray fluorescence, and thermal analysis (DTA and TGA). The results demonstrate the use of two types of earth
for the realisation of rammed earth, the first one non-plastic, -grained with added lime, the other one of low plasticity,
and fine grained without addition of lime. Mechanical tests on site and in laboratory how at the first type of material exhibits
great strength, exceeding the values known for rammed earth. 相似文献