Results Of 3D Model Research Articles

Energy and momentum preserving Coulomb collision model for kinetic Monte Carlo simulations of plasma steady states in toroidal fusion devices

A kinetic Monte Carlo model suited for self-consistent transport studies is proposed and tested. The Monte Carlo collision operator is based on a widely used model of Coulomb scattering by a drifting Maxwellian and a new algorithm enforcing the momentum and energy conservation laws. The difference to other approaches consists in a specific procedure of calculating the background Maxwellian parameters, which does not require ensemble averaging and, therefore, allows for the use of single-particle algorithms. This possibility is useful in transport balance (steady state) problems with a phenomenological diffusive ansatz for the turbulent transport, because it allows a direct use of variance reduction methods well suited for single particle algorithms. In addition, a method for the self-consistent calculation of the electric field is discussed. Results of testing of the new collision operator using a set of 1D examples, and preliminary results of 2D modelling in realistic tokamak geometry, are presented.

Calibration system for measuring the radon flux density

The measurement of radon flux from soil surface is the useful tool for the assessment of radon-prone areas and monitoring of radon releases from uranium mining and milling residues. The accumulation chambers with hollow headspace and chambers with activated charcoal are the most used devices for these purposes. Systematic errors of the measurements strongly depend on the geometry of the chamber and diffusion coefficient of the radon in soil. The calibration system for the attestation of devices for radon flux measurements was constructed. The calibration measurements of accumulation chambers and chambers with activated charcoal were conducted. The good agreement between the results of 2D modelling of radon flux and measurements results was observed. It was demonstrated that reliable measurements of radon flux can be obtained by chambers with activated charcoal (equivalent volume ~75 l) or by accumulation chambers with hollow headspace of ~7-10 l and volume/surface ratio (height) of >15 cm.

One‐dimensional and two‐dimensional hydrodynamic modeling derived flow properties: impacts on aquatic habitat quality predictions

AbstractStudies of the effects of hydrodynamic model dimensionality on simulated flow properties and derived quantities such as aquatic habitat quality are limited. It is important to close this knowledge gap especially now that entire river networks can be mapped at the microhabitat scale due to the advent of point‐cloud techniques. This study compares flow properties, such as depth and velocity, and aquatic habitat quality predicted from pseudo‐2D and fully 2D hydrodynamic modeling. The models are supported by high‐resolution, point‐cloud derived bathymetries, from which close‐spaced cross‐sections were extracted for the 1D modeling, of three morphologically and hydraulically different river systems. These systems range from small low‐gradient meandering pool–riffle to large steep confined plane‐bed rivers. We test the effects of 1D and 2D models on predicted hydraulic variables at cross‐sections and over the full bathymetry to quantify the differences due to model dimensionality and those from interpolation. Results show that streambed features, whose size is smaller than cross‐sectional spacing, chiefly determine the different results of 1D and 2D modeling whereas flow discharge, stream size, morphological complexity and model grid sizes have secondary effects on flow properties and habitat quality for a given species and life stage predicted from 1D and 2D modeling. In general, the differences in hydraulic variables are larger in the bathymetric than in the cross‐sectional analysis, which suggests that some errors are introduced from interpolation of spatially disaggregated simulated variables with a 1D model, instead of model dimensionality 1D or 2D. Flow property differences are larger for velocity than for water surface elevation and depth. Differences in weighted usable area (WUA) derived from 1D and 2D modeling are relatively small for low‐gradient meandering pool–riffle systems, but the differences in the spatial distribution of microhabitats can be considerable although clusters of same habitat quality are spatially comparable. Copyright © 2014 John Wiley & Sons, Ltd.

A practical numerical approach for prediction of particulate fouling in PC boilers

Particulate fouling of convective heat-transfer surfaces is usually assessed by empirical correlations. Nevertheless, constant progress in numerical calculation methods allows for prediction of deposition. This paper presents results of 2D modeling of powdery, medium-temperature deposit formation on superheater tubes. In contrast to other studies, presented approach results in shape prediction of deposits versus time of boiler operation. The mechanism includes the force of gravity, elastic rebound and adhesion forces acting at the moment of ash particle impaction. The forces determine if the particle bounces off the surface or stays onto it building up the deposit. Two practical cases are considered - an upward flue gas flow and a downward flow in the boiler. The results of simulations are compared with measurements in real boilers published earlier. The full-scale results are reproduced well. The simulations are carried out with use of Fluent code by means of User Defined Files. The described mechanism is implemented in Define_DPM_Erosion, and shape prediction is mirrored using Define_Grid_Motion functions of the Fluent code.

Heat flow in salt-dome basins of Eurasia: A comparative study

The geothermal fields in the Pericaspian, Pripyat, and North German basins are considered. These basins are characterized by widespread Upper Paleozoic evaporite sequences, which underwent halokinesis with the formation of salt domes and plugs owing to tectonic and gravity instability. Heat flow refraction occurs at the boundaries of the domes with country rocks due to the contrast in thermal conductivity of evaporites and terrigenous rocks between the domal zones. This is the main cause of heat flow variation in the lateral and vertical directions in the salt-dome basins. Close correlation between zones of elevated temperature in the sedimentary rocks and petroleum occurrences is confirmed by the results of 2D and 3D modeling of the geothermal field. The previously noted relations of oil and gas fields to the deep faults in the studied basins create prerequisites for consideration of the geothermal field as a genetic factor controlling the tectonic features and petroleum resources of the salt-dome basins.

Three-Dimentional Seismic Response Analysis of Semi-Submersible-Type Isolation Structure Based on Expanded Mild Slope Equations

Three-dimentional expanded mild-slope equation models were applied to seismic response analysis of semi-submersibletype isolation structure. Against horizontal vibration, damping effects caused by wave generation calculated by the 3Dmodel was relatively weak, and the peak of magnification factor indicated larger value than the results of 2D-model. We also estimated axial forces of rubber bearings under vertical and horizontal external vibration, and found that not only heaving but also rocking motion increases axial forces.

Electromagnetic Modeling of the AGS A10 Injection Kicker Magnet

The present Alternating Gradient Synchrotron (AGS) injection kicker magnets at the A5 location were designed for 1.5 GeV proton injection. Recent high intensity runs have pushed the transfer kinetic energy to 1.94 GeV, but with an imperfect matching in transverse phase space. Space charge forces result in both fast and slow beam size growth and beam loss. A proposed increase in the AGS injection energy to 2 GeV with adequate kick strength would greatly reduce the beam losses making it possible to increase the intensity from 70 TP (70*1012 protons/s) to 100 TP. RD the design goal is to achieve a field uniformity, for protons, of plusmn3% over 90% of the cross-sectional area of the aperture. TRIUMF has proposed a design for a 12.5 Omega transmission line kicker magnet powered by a matched 12.5 Omega pulse forming line. This paper presents the results of detailed 2D and 3D electromagnetic modeling of the kicker magnet, and a novel mathematical model of the kicker

Regulation technique for a large gap magnetic field for 3D non-contact manipulation

Magnetic levitation is a good choice for high precision micromanipulation. Several magnetic levitation systems have been proposed and shown to be effective for precision positioning. Most of these systems work with small air gaps and have a small movement range for levitated objects. Increasing the air gap will introduce uncertainty into the modeling and control of the system but is required for specific applications, such as micromanipulation. This paper investigates regulation methods and the control of a large gap magnetic field for non-contact manipulation. A two dimensional magnetic field analysis is performed on a system consists of two electromagnets. In order to increase the uniformity of the magnetic field and have control over the distribution of the field, the electromagnet poles are connected together through a soft magnetic iron called pole piece. The effect of pole piece is investigated through both finite element analysis and mathematical modeling. Definition of a working envelop through magnetic filed distribution is discussed. The results of 2D modeling are discussed and are extended into the 3D case. A number of pole piece profiles are proposed and their effect on the magnetic field investigated. An experimental setup is used for 3D levitated movement of a small permanent magnet. It is shown that manipulation of objects can be performed using an appropriate configuration of electromagnets, a special pole piece, and a yoke.

Crustal structure across the TESZ along POLONAISE'97 seismic profile P2 in NW Poland

The POLONAISE'97 ( POlish Lithospheric ONset— An International Seismic Experiment, 1997) seismic experiment in Poland targeted the deep structure of the Trans-European Suture Zone (TESZ) and the complex series of upper crustal features around the Polish Basin. One of the seismic profiles was the 300-km-long profile P2 in northwestern Poland across the TESZ. Results of 2D modelling show that the crustal thickness varies considerably along the profile: ∼29 km below the Palaeozoic Platform; 35–47 km at the crustal keel at the Teisseyre–Tornquist Zone (TTZ), slightly displaced to the northeast of the geologic inversion zone; and ∼42 km below the Precambrian Craton. In the Polish Basin and further to the south, the depth down to the consolidated basement is 6–14 km, as characterised by a velocity of 5.8–5.9 km/s. The low basement velocities, less than 6.0 km/s, extend to a depth of 16–22 km. In the middle crust, with a thickness of ca. 4–14 km, the velocity changes from 6.2 km/s in the southwestern to 6.8 km/s in the northeastern parts of the profile. The lower crust also differs between the southwestern and northeastern parts of the profile: from 8 km thickness, with a velocity of 6.8–7.0 km/s at a depth of 22 km, to ca.12 km thickness with a velocity of 7.0–7.2 km/s at a depth of 30 km. In the lowermost crust, a body with a velocity of 7.20–7.25 km/s was found above Moho at a depth of 33–45 km in the central part of the profile. Sub-Moho velocities are 8.2–8.3 km/s beneath the Palaeozoic Platform and TTZ, and about 8.1 km/s beneath the Precambrian Platform. Seismic reflectors in the upper mantle were interpreted at ∼45-km depth beneath the Palaeozoic Platform and ∼55-km depth beneath the TTZ. The Polish Basin is an up to 14-km-thick asymmetric graben feature. The basement beneath the Palaeozoic Platform in the southwest is similar to other areas that were subject to Caledonian deformation (Avalonia) such that the Variscan basement has only been imaged at a shallow depth along the profile. At northeastern end of the profile, the velocity structure is comparable to the crustal structure found in other portions of the East European Craton (EEC). The crustal keel may be related to the geologic inversion processes or to magmatic underplating during the Carboniferous–Permian extension and volcanic activity.

P velocity heterogeneities in the lower mantle determined with the German Regional Seismic Network: improvement of previous models and results of 2D modelling

P waves recorded at the German Regional Seismic Network (GRSN), the Gräfenberg-Array, the German Experiment Seismic System (GERESS) Mini-Array and two Czech stations are used to analyse the inhomogeneous lowermost mantle (D″) under Northern Siberia and the Nansen Basin. Events with a good signal-to-noise ratio are used to determine the extension of the anomaly. Relative travel time residuals compared with a 1D model with a relfector in D″ give information on the shape of the anomaly. Improved travel time residuals are derived by applying a source or/and station correction. This correction, which was not previously applied, reduces the size of the inferred peak to peak topography at the top of D″ by 20 km. If the sources are near lateral inhomogeneities, e.g. near the bend of a subduction zone, such corrections are necessary, otherwise models of D″ structure can be severely biased. Modelling of waveforms for such laterally inhomogeneous structures in D″ show strong effects on the wave field at dominant periods of 1 to 5 s, as multipathing of PdP (the P wave reflected at the top of D″), travel time differences and strong variations in amplitude, in agreement with the observations. Typical dimensions of such hills and valleys are 400 to 1200 km laterally and 10 to 100 km in topograph.