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Finite element modelling of interaction between surface and Darcy flow regimes through soils
The present work deals with the impact of surface flow on hydrodynamic conditions in saturated underground domains. A three dimensional finite element analysis of water flow has been used to obtain the required simulations. The results clearly show the effects of the surface flow on the hydrodynamic conditions of the subsurface porous regions. This analysis is an important prerequisite for the prediction of contaminant mobility in soils and hence provides a convenient tool for the prediction of environmentally important subsurface flow processes. For low permeability cases, considered here, governing equations consist of water continuity and Darcy equations. These equations are solved using a robust and reliable finite element procedure
Distributed simulation of city inundation by coupled surface and subsurface porous flow for urban flood decision support system
We present a decision support system for flood early warning and disaster
management. It includes the models for data-driven meteorological predictions,
for simulation of atmospheric pressure, wind, long sea waves and seiches; a
module for optimization of flood barrier gates operation; models for stability
assessment of levees and embankments, for simulation of city inundation
dynamics and citizens evacuation scenarios. The novelty of this paper is a
coupled distributed simulation of surface and subsurface flows that can predict
inundation of low-lying inland zones far from the submerged waterfront areas,
as observed in St. Petersburg city during the floods. All the models are
wrapped as software services in the CLAVIRE platform for urgent computing,
which provides workflow management and resource orchestration.Comment: Pre-print submitted to the 2013 International Conference on
Computational Scienc
Studying the thermal conductivity of a deep Eocene clay formation: direct measurements vs back-analysis results
An experimental study on Ypresian claysâone of the potential deep and sedimentary clay formations in Belgium for the geological disposal of heat-emitting radioactive wasteâhas been undertaken to systematically study its thermal conductivity using different experimental techniques. As a first step, a new experimental setup with heat flux measurement has been used and careful pre-conditioning protocols have been followed to directly measure this thermal property. The aim of these pre-conditioning tests has been ensuring a very high degree of saturation and the closure of fissures / gaps along bedding planes before the thermal tests are run under low stress conditions. Thermal tests have shown to be particularly sensitive when the thermal conductivity is determined along a direction orthogonal to these bedding planes. The study is then complemented by using a constant volume heating cell, in which heating pulse tests have been carried out under fully saturated conditions that have been ensured with a high water back-pressure. Numerical models have been used to interpret this pulse test, to exploit all the information provided by temperature measurements and to back-analyse the thermal conductivity. Direct thermal conductivity data with the improved pre-conditioning protocol allowed obtaining results consistent with the values reported when using back-analysis in the constant volume cell. The article discusses the importance of restoring full saturation conditions, particularly on retrieval of deep sedimentary clays, which may undergo opening of fissures along bedding planes that may affect the correct determination of the thermal conductivity.Peer ReviewedPostprint (author's final draft
DaMaSCUS: The Impact of Underground Scatterings on Direct Detection of Light Dark Matter
Conventional dark matter direct detection experiments set stringent
constraints on dark matter by looking for elastic scattering events between
dark matter particles and nuclei in underground detectors. However these
constraints weaken significantly in the sub-GeV mass region, simply because
light dark matter does not have enough energy to trigger detectors regardless
of the dark matter-nucleon scattering cross section. Even if future experiments
lower their energy thresholds, they will still be blind to parameter space
where dark matter particles interact with nuclei strongly enough that they lose
enough energy and become unable to cause a signal above the experimental
threshold by the time they reach the underground detector. Therefore in case
dark matter is in the sub-GeV region and strongly interacting, possible
underground scatterings of dark matter with terrestrial nuclei must be taken
into account because they affect significantly the recoil spectra and event
rates, regardless of whether the experiment probes DM via DM-nucleus or
DM-electron interaction. To quantify this effect we present the publicly
available Dark Matter Simulation Code for Underground Scatterings (DaMaSCUS), a
Monte Carlo simulator of DM trajectories through the Earth taking underground
scatterings into account. Our simulation allows the precise calculation of the
density and velocity distribution of dark matter at any detector of given depth
and location on Earth. The simulation can also provide the accurate recoil
spectrum in underground detectors as well as the phase and amplitude of the
diurnal modulation caused by this shadowing effect of the Earth, ultimately
relating the modulations expected in different detectors, which is important to
decisively conclude if a diurnal modulation is due to dark matter or an
irrelevant background.Comment: 33 pages including 20 figures and 4 appendices. The DaMaSCUS code is
available at https://github.com/temken/ . v2: matches the published versio
Three dimensional modelling of interaction between surface and Darcy flow regimes through soils
The present paper deals with the impact of surface flow on hydrodynamic conditions in saturated underground domains. A three dimensional finite element scheme has been used to simulate underground flow resulting from the flow of water over a saturated land. The results clearly show the effects of the surface flow on the hydrodynamic conditions of the subsurface porous regions. This analysis is an important prerequisite for the prediction of contaminant mobility in soils and hence provides a convenient tool for the prediction of interaction between surface and subsurface flow processes. For low permeability cases, considered here, the governing equations consist of water continuity and Darcy equations. These equations are solved using a robust and reliable finite element procedure
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