Rendering technique of multi-layered domain boundaries and its application to fluid flow in porous media visualizations     

Dmitri Naumov  Lars Bilke  Olaf Kolditz 《Environmental Earth Sciences》2014,72(10):3795-3802

Current visualization techniques for computational fluid dynamics applications are sophisticated and work well in simple geometries. For complex geometries such as pore spaces, multiple domain boundaries obstruct the view and make the studying of fluid flow fields difficult. To overcome these deficiencies, we use two-sided materials to render the domain boundaries. Using this technique, it is possible to place the camera inside the domain and have a non-obstructed view of the surrounding flow field without losing spatial reference to the domain boundaries. As a result, a larger part of fluid flow visualization is visible. Two-sided material rendering was successfully applied to display still images with Blender Cycles renderer, in a virtual reality environment, and several implementation techniques were explored for using the Visualization Toolkit.  相似文献   

TESSIN VISLab—laboratory for scientific visualization     

Lars Bilke  Thomas Fischer  Carolin Helbig  Charlotte Krawczyk  Thomas Nagel  Dmitri Naumov  Sebastian Paulick  Karsten Rink  Agnes Sachse  Sophie Schelenz  Marc Walther  Norihiro Watanabe  Björn Zehner  Jennifer Ziesch  Olaf Kolditz 《Environmental Earth Sciences》2014,72(10):3881-3899

Scientific visualization is an integral part of the modeling workflow, enabling researchers to understand complex or large data sets and simulation results. A high-resolution stereoscopic virtual reality (VR) environment further enhances the possibilities of visualization. Such an environment also allows collaboration in work groups including people of different backgrounds and to present results of research projects to stakeholders or the public. The requirements for the computing equipment driving the VR environment demand specialized software applications which can be run in a parallel fashion on a set of interconnected machines. Another challenge is to devise a useful data workflow from source data sets onto the display system. Therefore, we develop software applications like the OpenGeoSys Data Explorer, custom data conversion tools for established visualization packages such as ParaView and Visualization Toolkit as well as presentation and interaction techniques for 3D applications like Unity. We demonstrate our workflow by presenting visualization results for case studies from a broad range of applications. An outlook on how visualization techniques can be deeply integrated into the simulation process is given and future technical improvements such as a simplified hardware setup are outlined.  相似文献   

On the equatorward phase propagation of high-m ULF pulsations observed by radars     

Pavel N. Mager  Dmitri Yu. Klimushkin  Nickolay Ivchenko 《Journal of Atmospheric and Solar》2009,71(16):1677-1680

An often observed and still unexplained feature of the high-m Alfvén waves in the terrestrial magnetosphere is their equatorward phase motion, in contrast with low-m waves. We suggest an explanation of this fact in terms of a model of wave excitation by an azimuthally drifting particle inhomogeneity injected during substorm activity. The azimuthal direction of the phase velocity coincides with that of the cloud. If the drift velocity increases with the radial coordinate, the particle cloud is stretched into spiral in the equatorial plane which leads to a radial component of the phase velocity directed toward Earth, that is, an equatorward phase propagation.  相似文献   

Imaging DOAS for volcanological applications     

Ilia Louban  Nicole Bobrowski  Dmitri Rouwet  Salvatore Inguaggiato  Ulrich Platt 《Bulletin of Volcanology》2009,71(7):753-765

The simultaneous quantitative determination of two-dimensional bromine monoxide (BrO) and sulphur dioxide (SO₂) distributions in volcanic gas plumes is described. Measurements at the fumarolic field on the island Vulcano (autumn 2004) and in the plume of Mt. Etna volcano (spring 2005) were carried out with an Imaging DOAS instrument. The SO₂ fluxes of several fumaroles were estimated from two-dimensional distributions of SO₂. Additionally, the first two-dimensional distributions of BrO within a volcanic plume were successfully retrieved. Slant column densities of up to 2.6 × 10¹⁴ molecules per square centimetre were detected in the plume of Mt. Etna. The investigation of the BrO/SO₂ ratio, calculated from the two-dimensional distributions of SO₂ and BrO, shows an increase from the centre to the edge of the volcanic plume. These results have significance for the involvement of ozone during BrO formation processes in volcanic emissions.  相似文献   

Lithospheric mantle beneath the south-eastern Siberian craton: petrology of peridotite xenoliths in basalts from the Tokinsky Stanovik     

Dmitri?A.?IonovEmail author  Vladimir?S.?Prikhodko  Jean-Louis?Bodinier  Alexander?V.?Sobolev  Dominique?Weis 《Contributions to Mineralogy and Petrology》2005,149(6):647-665

We provide petrographic, major and trace element data for over 30 spinel peridotite xenoliths from the Tokinsky Stanovik (Tok) volcanic field on the Aldan shield to characterize the lithospheric mantle beneath the south-eastern margin of the Siberian craton, which formed in the Mesoproterozoic. High equilibration temperatures (870–1,010°C) of the xenoliths and the absence of garnet-bearing peridotites indicate a much thinner lithosphere than in the central craton. Most common among the xenoliths are clinopyroxene-poor lherzolites and harzburgites with Al₂O₃ and CaO contents nearly as low as in refractory xenoliths from kimberlite pipes (Mir, Udachnaya) in the central and northern Siberian craton. By contrast, the Tok peridotites have higher FeO, lower Mg-numbers and lower modal orthopyroxene and are apparently formed by shallow partial melting (3 GPa). Nearly all Tok xenoliths yield petrographic and chemical evidence for metasomatism: accessory phlogopite, amphibole, phosphates, feldspar and Ti-rich oxides, very high Na₂O (2–3.1%) in clinopyroxene, LREE enrichments in whole-rocks.Electronic Supplementary Material Supplementary material is available for this article at  相似文献   

Weighting and smoothing of stomach content data as input for MSVPA with particular reference to the Barents Sea     

Bulgakova  Tatiana; Vasilyev  Dmitri; Daan  Niels 《ICES Journal of Marine Science》2001,58(6):1208-1218

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Impacts of frontal stability and topography on cross-shelf exchange in the Northern Gulf of Mexico     

Nadya T. Vinogradova  Dmitri A. Nechaev 《Journal of Oceanography》2006,62(5):667-680

The shelfbreak wintertime thermal front in the Northeastern Gulf of Mexico often exhibits meandering, eddy formation and warm-water intrusion. A high level of frontal variability plays an essential role in exchange processes across the shelf. This study examines the impacts of local frontal instability and bottom topography on turbulent heat exchange across the front using the results of two numerical models. Analysis of a series of numerical experiments reveals that the flow is baroclinically unstable. Predicted frontal instability contributes significantly to cross-frontal exchange and accounts for about 35% of the total eddy heat flux. Onshore eddy heat flux has the highest intensity at the frontal position. In addition, eddy activity and heat flux are sensitive to variation of bottom topography. For topographic features and frontal characteristics that are typical of the area, bottom steepness enhances the flux and is nearly proportional to the cross-frontal heat exchange. The study attempts to explain physical mechanisms that drive frontal circulation in the area and to quantify heat transport across the shelf. Estimated heat fluxes can provide important information for climate and ecosystem modeling of the Mississippi Bight.  相似文献   

Mass, Heat and Salt Balances in the Eastern Barents Sea Obtained by Inversion of Hydrographic Section Data     

Gleb Panteleev  Motoyoshi Ikeda  Alex Grotov  Dmitri Nechaev  Max Yaremchuk 《Journal of Oceanography》2004,60(3):613-623

Standard hydrological section data, collected in the eastern Barents Sea in September 1997, have been analyzed using a variational data assimilation technique. This method allows us to obtain temperature, salinity and velocity fields that are consistent with observations and dynamically balanced within the framework of a steady-state model describing large-scale nearly geostrophic circulation. Error bars of the optimized fields are computed by explicit inversion of the Hessian matrix. The optimized velocity field is in agreement with independent velocity observations derived from surface drifter trajectories in the southwestern part of the Barents Sea. Optimized fields provide the following estimates of integral characteristics of the circulation in the region: i) the North Cape current transport is 2.12 ± 0.25 Sv; ii) the Karskie Vorota Strait throughflow is 0.7 ± 0.06 Sv; iii) heat flux with Atlantic water is 4.7 ± 0.16⋅10¹¹ W; iv) salt import from the Atlantic Ocean is 7.41 ± 0.46⋅10³ kg/s. The imbalance of the heat budget in the eastern part of the Barents Sea indicates the presence of statistically insignificant surface heat fluxes which are less than 1 W/m². This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Pressure ionization of hydrogen and helium     

A. I. Pisarenko  A. A. Yatsenko 《Astronomy Reports》2008,52(11):937-940

Simple empirical formulas that can be used to calculate the lowering of the ionization potentials of hydrogen and helium due to the quantum-mechanical repulsion of particles in a dense plasma at small separations are presented. The formula for atomic hydrogen is a good approximation to exact quantum-mechanical calculations for hydrogen plasma, as well as data from modeling of plasma phase transitions in dense hydrogen using a modified Monte-Carlo method. The formula for helium agrees well with theoretical calculations for pressure ionization of helium.  相似文献   

Behind every robust result is a robust method: Perspectives from a case study and publication process in hydrological modelling     

Fabrizio Fenicia  Dmitri Kavetski 《水文研究》2021,35(8):e14266

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