3-D Relativistic MHD Simulations
Nishikawa, K.-I.; Frank, J.; Koide, S.; Sakai, J.-I.; Christodoulou, D. M.; Sol, H.; Mutel, R. L.
1998-12-01
We present 3-D numerical simulations of moderately hot, supersonic jets propagating initially along or obliquely to the field lines of a denser magnetized background medium with Lorentz factors of W = 4.56 and evolving in a four-dimensional spacetime. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently in the simulations. This effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure.
INCORPORATING DYNAMIC 3D SIMULATION INTO PRA
Steven R Prescott; Curtis Smith
2011-07-01
Through continued advancement in computational resources, development that was previously done by trial and error production is now performed through computer simulation. These virtual physical representations have the potential to provide accurate and valid modeling results and are being used in many different technical fields. Risk assessment now has the opportunity to use 3D simulation to improve analysis results and insights, especially for external event analysis. By using simulations, the modeler only has to determine the likelihood of an event without having to also predict the results of that event. The 3D simulation automatically determines not only the outcome of the event, but when those failures occur. How can we effectively incorporate 3D simulation into traditional PRA? Most PRA plant modeling is made up of components with different failure modes, probabilities, and rates. Typically, these components are grouped into various systems and then are modeled together (in different combinations) as a “system” with logic structures to form fault trees. Applicable fault trees are combined through scenarios, typically represented by event tree models. Though this method gives us failure results for a given model, it has limitations when it comes to time-based dependencies or dependencies that are coupled to physical processes which may themselves be space- or time-dependent. Since, failures from a 3D simulation are naturally time related, they should be used in that manner. In our simulation approach, traditional static models are converted into an equivalent state diagram representation with start states, probabilistic driven movements between states and terminal states. As the state model is run repeatedly, it converges to the same results as the PRA model in cases where time-related factors are not important. In cases where timing considerations are important (e.g., when events are dependent upon each other), then the simulation approach will typically
3D Molecular dynamics simulations using spheropolytopes
Galindo-Torres, Sergio-Andres; Alonso-Marroquin, Fernando; Wang, Yucang
2008-01-01
We present a simple and efficient method to simulate three-dimensional, complex-shaped, interacting bodies. The particle shape is represented by Minkowski operators. A time-continuous interaction between these bodies is derived using simple concepts of computational geometry. The model (particles + interactions) is efficient, accurate and easy to implement, and it complies with the conservation laws of physics. 3D simulations of hopper flow shows that the non-convexity of the particles strong...
3D FDTD simulations of photonic devices
Full text: In our contribution we will present the recent results on 3D simulations of photonic devices. Particularly, quantum well infrared photodetectors with embedded photonic crystal are optimized to achieve optimal light coupling and quantum efficiency. Furthermore, we study schemes of light coupling into SOI waveguides. Both optical fibre-SOI waveguide and laser-SOI waveguide coupling schemes are investigated. The results of investigations regarding the influence of disorder on the reflection peak in opal 3D photonic crystal will be also presented. This work was supported by the Austrian Nanoinitiative RPC PLATON. (author)
Simulating coronal condensation dynamics in 3D
Moschou, S P; Xia, C; Fang, X
2015-01-01
We present numerical simulations in 3D settings where coronal rain phenomena take place in a magnetic configuration of a quadrupolar arcade system. Our simulation is a magnetohydrodynamic simulation including anisotropic thermal conduction, optically thin radiative losses, and parametrised heating as main thermodynamical features to construct a realistic arcade configuration from chromospheric to coronal heights. The plasma evaporation from chromospheric and transition region heights eventually causes localised runaway condensation events and we witness the formation of plasma blobs due to thermal instability, that evolve dynamically in the heated arcade part and move gradually downwards due to interchange type dynamics. Unlike earlier 2.5D simulations, in this case there is no large scale prominence formation observed, but a continuous coronal rain develops which shows clear indications of Rayleigh-Taylor or interchange instability, that causes the denser plasma located above the transition region to fall do...
Radiative Transfer in 3D Numerical Simulations
Stein, R; Stein, Robert; Nordlund, Aake
2002-01-01
We simulate convection near the solar surface, where the continuum optical depth is of order unity. Hence, to determine the radiative heating and cooling in the energy conservation equation, we must solve the radiative transfer equation (instead of using the diffusion or optically thin cooling approximations). A method efficient enough to calculate the radiation for thousands of time steps is needed. We assume LTE and a non-gray opacity grouped into 4 bins according to strength. We perform a formal solution of the Feautrier equation along a vertical and four straight, slanted, rays (at four azimuthal angles which are rotated 15 deg. every time step). We present details of our method. We also give some results: comparing simulated and observed line profiles for the Sun, showing the importance of 3D transfer for the structure of the mean atmosphere and the eigenfrequencies of p-modes, illustrating Stokes profiles for micropores, and analyzing the effect of radiation on p-mode asymmetries.
3D electrohydrodynamic simulation of electrowetting displays
The fluid dynamic behavior within a pixel of an electrowetting display (EWD) is thoroughly investigated through a 3D simulation. By coupling the electrohydrodynamic (EHD) force deduced from the Maxwell stress tensor with the laminar phase field of the oil–water dual phase, the complete switch processes of an EWD, including the break-up and the electrowetting stages in the switch-on process (with voltage) and the oil spreading in the switch-off process (without voltage), are successfully simulated. By considering the factor of the change in the apparent contact angle at the contact line, the electro–optic performance obtained from the simulation is found to agree well with its corresponding experiment. The proposed model is used to parametrically predict the effect of interfacial (e.g. contact angle of grid) and geometric (e.g. oil thickness and pixel size) properties on the defects of an EWD, such as oil dewetting patterns, oil overflow, and oil non-recovery. With the help of the defect analysis, a highly stable EWD is both experimentally realized and numerically analyzed. (paper)
Planning for brachytherapy using a 3D-simulation model
A 3D-simulation model made with a milling system was applied to HDR-brachytherapy. The 3D-simulation model is used to simulate the 3D-structure of the lesion and the surrounding organs before the actual catheterization for brachytherapy. The first case was recurrent prostatic cancer in a 61-year-old man. The other case was lymph node recurrence of a 71-year-old woman's upper gum cancer. In both cases, the 3D-simulation model was very useful to simulate the 3D-conformation, to plan the treatment process and to avoid the risk accompanying treatment. (author)
Numerical simulation of 3D breaking waves
Fraunie, Philippe; Golay, Frederic
2015-04-01
Numerical methods dealing with two phase flows basically can be classified in two ways : the "interface tracking" methods when the two phases are resolved separately including boundary conditions fixed at the interface and the "interface capturing" methods when a single flow is considered with variable density. Physical and numerical properties of the two approaches are discussed, based on some numerical experiments performed concerning 3D breaking waves. Acknowledgements : This research was supported by the Modtercom program of Region PACA.
3D Magnetron simulation with CST STUDIO SUITE
The modeling of magnetrons compared to other tubes is more difficult since it requires 3D modeling rather than a 2D investigation. This is not only due to the geometry which can include complicated details to be modeled in 3D but also due to the interaction process itself. The electric field, magnetic field and particle movement span a 3D space. In this paper 3D simulations of a strapped magnetron with CSTSTUDIO SUITETM are presented. (author)
Charge collection characterization of a 3D silicon radiation detector by using 3D simulations
Kalliopuska, J; Orava, R
2007-01-01
In 3D detectors, the electrodes are processed within the bulk of the sensor material. Therefore, the signal charge is collected independently of the wafer thickness and the collection process is faster due to shorter distances between the charge collection electrodes as compared to a planar detector structure. In this paper, 3D simulations are used to assess the performance of a 3D detector structure in terms of charge sharing, efficiency and speed of charge collection, surface charge, location of the primary interaction and the bias voltage. The measured current pulse is proposed to be delayed due to the resistance–capacitance (RC) product induced by the variation of the serial resistance of the pixel electrode depending on the depth of the primary interaction. Extensive simulations are carried out to characterize the 3D detector structures and to verify the proposed explanation for the delay of the current pulse. A method for testing the hypothesis experimentally is suggested.
3D HYDRA Simulations of NIF Targets
Marinak, M M; Kerbel, G D; Gentile, N A; Jones, O; Pollaine, S; Dittrich, T R; Haan, S W
2000-10-20
The performance of NIF target designs is simulated in three dimensions using the HYDRA multiphysics radiation hydrodynamics code. In simulations of a cylindrical NIF hohlraum that include an imploding capsule, the motion of the wall material inside the hohlraum shows a high degree of axisymmetry. Laser radiation is able to propagate through the entrance hole for the required duration of the pulse. Gross hohlraum energetics in the simulation mirror the results from an axisymmetric simulation. A simulation of a copper-doped beryllium ablator NIF capsule carried out over large solid angle resolved the full spectrum of the most dangerous modes that grow from surface roughness. Hydrodynamic instabilities evolve into the weakly nonlinear regime. There is no evidence of low mode jetting driven by nonlinear mode coupling.
3D HYDRA simulations of NIF targets
Marinak, M M; Kerbel, G D; Gentile, N A; Jones, O; Munro, D; Pollaine, S; Dittrich, T R; Haan, S W
2000-10-30
The performance of NIF target designs is simulated in three dimensions using the HYDRA multiphysics radiation hydrodynamics code. In simulations of a cylindrical NIF hohlraum that include an imploding capsule, all relevant hohlraum features and the detailed laser illumination pattern, the motion of the wall material inside the hohlraum shows a high degree of axisymmetry. Laser light is able to propagate through the entrance hole for the required duration of the pulse. Gross hohlraum energetics mirror the results from an axisymmetric simulation. A NIF capsule simulation resolved the full spectrum of the most dangerous modes that grow from surface roughness. Hydrodynamic instabilities evolve into the weakly nonlinear regime. There is no evidence of anomalous low mode growth driven by nonlinear mode coupling.
3D visualization of port simulation.
Horsthemke, W. H.; Macal, C. M.; Nevins, M. R.
1999-06-14
Affordable and realistic three dimensional visualization technology can be applied to large scale constructive simulations such as the port simulation model, PORTSIM. These visualization tools enhance the experienced planner's ability to form mental models of how seaport operations will unfold when the simulation model is implemented and executed. They also offer unique opportunities to train new planners not only in the use of the simulation model but on the layout and design of seaports. Simulation visualization capabilities are enhanced by borrowing from work on interface design, camera control, and data presentation. Using selective fidelity, the designers of these visualization systems can reduce their time and efforts by concentrating on those features which yield the most value for their simulation. Offering the user various observational tools allows the freedom to simply watch or engage in the simulation without getting lost. Identifying the underlying infrastructure or cargo items with labels can provide useful information at the risk of some visual clutter. The PortVis visualization expands the PORTSIM user base which can benefit from the results provided by this capability, especially in strategic planning, mission rehearsal, and training. Strategic planners will immediately reap the benefits of seeing the impact of increased throughput visually without keeping track of statistical data. Mission rehearsal and training users will have an effective training tool to supplement their operational training exercises which are limited in number because of their high costs. Having another effective training modality in this visualization system allows more training to take place and more personnel to gain an understanding of seaport operations. This simulation and visualization training can be accomplished at lower cost than would be possible for the operational training exercises alone. The application of PORTSIM and PortVis will lead to more efficient
3D MHD Simulations of Spheromak Compression
Stuber, James E.; Woodruff, Simon; O'Bryan, John; Romero-Talamas, Carlos A.; Darpa Spheromak Team
2015-11-01
The adiabatic compression of compact tori could lead to a compact and hence low cost fusion energy system. The critical scientific issues in spheromak compression relate both to confinement properties and to the stability of the configuration undergoing compression. We present results from the NIMROD code modified with the addition of magnetic field coils that allow us to examine the role of rotation on the stability and confinement of the spheromak (extending prior work for the FRC). We present results from a scan in initial rotation, from 0 to 100km/s. We show that strong rotational shear (10km/s over 1cm) occurs. We compare the simulation results with analytic scaling relations for adiabatic compression. Work performed under DARPA grant N66001-14-1-4044.
3-D template simulation system in Total Hip Arthroplasty
In Total Hip Arthroplastry, 2D template on Plain X-ray is usually used for preoperative planning. But deformity and contracture can cause malposition and measurement error. To reduce those problems, a 3D preoperative simulation system was developed. Three methods were compared in this study. One is to create very accurate AP and ML images which can use for standard 2D template. One is fully 3D preoperative template system using computer graphics. Last one is substantial simulation using stereo-lithography model. 3D geometry data of the bone was made from Helical 3-D CT data. AP and ML surface cutting 3D images of the femur were created using workstation (Advantage Workstation; GE Medical Systems). The extracted 3D geometry was displayed on personal computer using Magics (STL data visualization software), then 3D geometry of the stem was superimposed in it. The full 3D simulation system made it possible to observe the bone and stem geometry from any direction and by any section view. Stereo-lithography model was useful for detailed observation of the femur anatomy. (author)
Numerical Relativity Towards Simulations of 3D Black Hole Coalescence
Seidel, E
1998-01-01
I review recent developments in numerical relativity, focussing on progress made in 3D black hole evolution. Progress in development of black hole initial data, apparent horizon boundary conditions, adaptive mesh refinement, and characteristic evolution is highlighted, as well as full 3D simulations of colliding and distorted black holes. For true 3D distorted holes, with Cauchy evolution techniques, it is now possible to extract highly accurate, nonaxisymmetric waveforms from fully nonlinear simulations, which are verified by comparison to pertubration theory, and with characteristic techniques extremely long term evolutions of 3D black holes are now possible. I also discuss a new code designed for 3D numerical relativity, called Cactus, that will be made public.
Simulations on 3D shape tracking with fibre Bragg gratings
Hooft 't, G.W.; Tirard-Gâtel, A.
2010-01-01
This report deals with the development of a reconstruction algorithm of 3D optical shape sensing. The theoretical frame work is established and simulations are performed for a multicore fiber system without torque.
Web 3D technology for virtual simulation for radiotherapy
Virtual Simulation of patient set-up for radiotherapy using Digitally Reconstructed Radiographs (DRRs) is becoming popular because of the advantages of higher precision and flexibility in planning at a lower cost. This technology is based on 2D concepts, as the DRR is a 2D image on which beam portals are planned. Web 3D technology is an emerging concept based on true 3D objects
Statistical 3D damage accumulation model for ion implant simulators
Hernandez-Mangas, J M; Enriquez, L E; Bailon, L; Barbolla, J; Jaraiz, M
2003-01-01
A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided.
Čillo, Vladimír
2015-01-01
Tato bakalářská práce se zabýva návrhem a implementací simulátoru 3D tiskárny v jazyce C++ s využitím knihovny Qt. Simulátor předpokládá tiskárnu založenou na nejrozšířenější metodě 3D tisku - Fused Deposition Modeling. Vstupem simulátoru je 3D model ve formátu STL. Pro daný 3D model simulátor poskytuje odhad celkové doby tisku. Součástí simulace je také vizualizace procesu 3D tisku. Výsledkem práce je přenositelný program testovaný pod operačními systémy Linux a Windows. Funkčnost simulátoru...
3D Simulations of line emission from ICF capsules
Line emission from ICF implosions can be used to diagnose the temperature of the DT fuel and provides an indication of the distortion in the fuel-pusher interface. 2D simulations have provided valuable insights into the usefulness of argon and titanium dopants as diagnostics of instabilities. Characterizing the effects of drive asymmetries requires 3D modeling with large demands for computer time and memory, necessitating the use of parallel computers. We present the results of some 3D simulations achieved with a code utilizing both shared memory and distributed parallelism. We discuss the code structure and related performance issues
3D Fiber Orientation Simulation for Plastic Injection Molding
Lin, Baojiu; Jin, Xiaoshi; Zheng, Rong; Costa, Franco S.; Fan, Zhiliang
2004-06-01
Glass fiber reinforced polymer is widely used in the products made using injection molding processing. The distribution of fiber orientation inside plastic parts has direct effects on quality of molded parts. Using computer simulation to predict fiber orientation distribution is one of most efficient ways to assist engineers to do warpage analysis and to find a good design solution to produce high quality plastic parts. Fiber orientation simulation software based on 2-1/2D (midplane /Dual domain mesh) techniques has been used in industry for a decade. However, the 2-1/2D technique is based on the planar Hele-Shaw approximation and it is not suitable when the geometry has complex three-dimensional features which cannot be well approximated by 2D shells. Recently, a full 3D simulation software for fiber orientation has been developed and integrated into Moldflow Plastics Insight 3D simulation software. The theory for this new 3D fiber orientation calculation module is described in this paper. Several examples are also presented to show the benefit in using 3D fiber orientation simulation.
3-D MHD Numerical Simulations of Cloud-Wind Interactions
Gregori, G.; Miniati, Francesco; Ryu, Dongsu; Jones, T. W.
2000-01-01
We present results from three-dimensional (3-D) numerical simulations investigating the magnetohydrodynamics of cloud-wind interactions. The initial cloud is spherical while the magnetic field is uniform and transverse to the cloud motion. A simplified analytical model that describes the magnetic energy evolution in front of the cloud is developed and compared with simulation results. In addition, it is found the interaction of the cloud with a magnetized interstellar medium (ISM) results in ...
3D Visualization and Simulation of the Human Navigation System
Hjelle, Henrik
2015-01-01
The aim of this thesis is to investigate how 3D visualizations and virtual reality can be used to make the human navigation system understandable for the general public. To do this, a 3D visualization of the human navigation systems components in the brain was created using Second Life. In addition, a simulation of how the cells in this system works was created with the same platform. These two types of visualization were used to see if they gave any learning outcome in relation to the ...
3D Simulation of Nano-Imprint Lithography
Román Marín, José Manuel; Rasmussen, Henrik K.; Hassager, Ole
2010-01-01
A proof of concept study of the feasibility of fully three-dimensional (3D) time-dependent simulation of nano-imprint lithography of polymer melt, where the polymer is treated as a structured liquid, has been presented. Considering the flow physics of the polymer as a structured liquid, we have...... followed the line initiated by de Gennes, using a Molecular Stress Function model of the Doi and Edwards type. We have used a 3D Lagrangian Galerkin finite element methods implemented on a parallel computer architecture. In a Lagrangian techniques, the node point follows the particle movement, allowing...
Direct numerical simulation of 3D transitional fluid flows
Full text: For the numerical simulation of the 2D-3D transitional homogeneous and stratified incompressible viscous fluid flows, characterizing by the full Navier-Stokes equations, the splitting on physical factors method is used. The explicit hybrid finite difference scheme of the method has the following behaviors: the second order of accuracy in space, minimum scheme viscosity and dispersion, workable in wide range of Reynolds and Froude numbers and monotonicity. The efficiency of the developed numerical method and the advanced performance of the supercomputers allowed simulating 2D-3D transitional uncompressible viscous fluid flows around the bluff bodies in particular around a cylinder. By the numerical simulation of the fluid flows around 3D circular cylinder it was found that the transition to 3D regime arrives at Re>200. At 200< Re<300 the mode A with wavelength 3.5 d<λ<4.0 d (where d is the diameter of the cylinder) for 3D structures along the axis of a cylinder was observed. At 300< Re<400 the mode B with wavelength 0.8 d<λ<0.9 d was observed. At Re=300 the both modes A and B were observed simultaneously. The regime with large dislocations previously discovered experimentally was first obtained numerically at 210< Re<260. This regime is characterized by flow phase dislocation along the axis of the cylinder and as the effect by the amplitude fall of the lift force coefficient and the variations in the drag coefficient. There was simulated numerically the initiation of the attached internal waves behind the circular cylinder and upstream disturbance area at low Froude and moderate Reynolds numbers. (author)
APROS 3-D core models for simulators and plant analyzers
The 3-D core models of APROS simulation environment can be used in simulator and plant analyzer applications, as well as in safety analysis. The key feature of APROS models is that the same physical models can be used in all applications. For three-dimensional reactor cores the APROS models cover both quadratic BWR and PWR cores and the hexagonal lattice VVER-type cores. In APROS environment the user can select the number of flow channels in the core and either five- or six-equation thermal hydraulic model for these channels. The thermal hydraulic model and the channel description have a decisive effect on the calculation time of the 3-D core model and thus just these selection make at present the major difference between a safety analysis model and a training simulator model. The paper presents examples of various types of 3-D LWR-type core descriptions for simulator and plant analyzer use and discusses the differences of calculation speed and physical results between a typical safety analysis model description and a real-time simulator model description in transients. (author)
3D simulation of CANDU reactor regulating system
Present paper shows the evaluation of the performance of the 3-D modal synthesis based reactor kinetic model in a closed-loop environment in a MATLAB/SIMULINK based Reactor Regulating System (RRS) simulation platform. A notable advantage of the 3-D model is the level of details that it can reveal as compared to the coupled point kinetic model. Using the developed RRS simulation platform, the reactor internal behaviours can be revealed during load-following tests. The test results are also benchmarked against measurements from an existing (CANDU) power plant. It can be concluded that the 3-D reactor model produces more realistic view of the core neutron flux distribution, which is closer to the real plant measurements than that from a coupled point kinetic model. It is also shown that, through a vectorization process, the computational load of the 3-D model is comparable with that of the 14-zone coupled point kinetic model. Furthermore, the developed Graphical User Interface (GUI) software package for RRS implementation represents a user friendly and independent application environment for education training and industrial utilizations. (authors)
3D simulation of coaxial carbon nanotube field effect transistor
We provide a model of coaxial CNTFET geometry. Coaxial devices are of special interest because their geometry allows for better electrostatics. We explore the possibilities of using non-equilibrium Green's function method to get I-V characteristics for CNTFETs. This simulator also includes a graphic user interface (GUI) of Matlab. We review the capabilities of the simulator, and give examples of typical CNTFET's 3D simulations (current-voltage characteristics are a function of parameters such as the length of CNTFET, gate thickness and temperature). The obtained I-V characteristics of the CNTFET are also presented by analytical equations.
Fast 3D stereo flood simulations in urban areas
Hoes, O.; de Haan, G.; Stelling, G.; van Leeuwen, E.; van Dam, A.; Pleumeekers, O.; Schuurmans, W.
2012-04-01
Flood propagation models are essential to study floods as it is problematic to collect data during actual floods. Moreover, models are needed to explore the consequences of additional scenarios above the actual flood itself. The results of these model studies are generally graphs with water levels over time for certain locations or maps with the flood extent in an area for different return periods. A main difficulty with these depictions of flood information is that they do not reflect the seriousness of flood impacts well in terms of life-like human experience. Typically, one needs a (near) flood before measures are implemented. Apparently, a graph or map is not the proper material to convince politicians and policy makers, even if they live in the threatened area. The recent introduction of commercially available 3D stereo projectors and high resolution elevation data make it possible to build life-like visualizations of simulations. In our research we explored using 3D stereo, the recently collected elevation data of the Netherlands (20 laser points per m2!) in combination with aerial photographs, and a new fast 2D flood propagation calculation scheme. This scheme (under construction) is able to simulate floods using such high amounts of data points. The model simulates flood propagation on an irregular grid; at locations with large elevation differences (e.g. in urban areas) and fast flowing water, smaller cells are used compared to flat surfaces where the water is not or hardly flowing. The result of our combination is a very detailed flood simulation model that can be used to simulate floods within a fraction of the current calculation time. The opportunities of models and their results increase enormously with fast calculations and visualizations combined. For example, the model allows on the spot exploration of measures during a flood, with the 3D visualization ensuring that flood impacts become clear for decision makers. We will show the preliminary
A FLOSS Visual EM Simulator for 3D Antennas
Koutsos, Christos A; Zimourtopoulos, Petros E
2010-01-01
This paper introduces the FLOSS Free Libre Open Source Software [VEMSA3D], a contraction of "Visual Electromagnetic Simulator for 3D Antennas", which are geometrically modeled, either exactly or approximately, as thin wire polygonal structures; presents its GUI Graphical User Interface capabilities, in interactive mode and/or in handling suitable formed antenna data files; demonstrates the effectiveness of its use in a number of practical antenna applications, with direct comparison to experimental measurements and other freeware results; and provides the inexperienced user with a specific list of instructions to successfully build the given source code by using only freely available IDE Integrated Development Environment tools-including a cross-platform one. The unrestricted access to source code, beyond the ability for immediate software improvement, offers to independent users and volunteer groups an expandable, in any way, visual antenna simulator, for a genuine research and development work in the field ...
Comparative visual analysis of 3D urban wind simulations
Röber, Niklas; Salim, Mohamed; Grawe, David; Leitl, Bernd; Böttinger, Michael; Schlünzen, Heinke
2016-04-01
Climate simulations are conducted in large quantity for a variety of different applications. Many of these simulations focus on global developments and study the Earth's climate system using a coupled atmosphere ocean model. Other simulations are performed on much smaller regional scales, to study very small fine grained climatic effects. These microscale climate simulations pose similar, yet also different, challenges for the visualization and the analysis of the simulation data. Modern interactive visualization and data analysis techniques are very powerful tools to assist the researcher in answering and communicating complex research questions. This presentation discusses comparative visualization for several different wind simulations, which were created using the microscale climate model MITRAS. The simulations differ in wind direction and speed, but are all centered on the same simulation domain: An area of Hamburg-Wilhelmsburg that hosted the IGA/IBA exhibition in 2013. The experiments contain a scenario case to analyze the effects of single buildings, as well as examine the impact of the Coriolis force within the simulation. The scenario case is additionally compared with real measurements from a wind tunnel experiment to ascertain the accuracy of the simulation and the model itself. We also compare different approaches for tree modeling and evaluate the stability of the model. In this presentation, we describe not only our workflow to efficiently and effectively visualize microscale climate simulation data using common 3D visualization and data analysis techniques, but also discuss how to compare variations of a simulation and how to highlight the subtle differences in between them. For the visualizations we use a range of different 3D tools that feature techniques for statistical data analysis, data selection, as well as linking and brushing.
NECTAR: Simulation and Visualization in a 3D Collaborative Environment
Law, Y.W.; Chan, K. Y.
2002-01-01
For simulation and visualization in a 3D collaborative environment, an architecture called the Nanyang Experimental CollaboraTive ARchitecture (NECTAR) has been developed. The objective is to support multi-user collaboration in a virtual environment with an emphasis on cost-effectiveness and interoperability. The architecture is based on the modular decomposition of a virtual environment system into three basic components: the graphics engine, the user interaction engine, and the networking e...
3D simulation of the Cluster-Cluster Aggregation model
Li, Chao; Xiong, Hailing
2014-12-01
We write a program to implement the Cluster-Cluster Aggregation (CCA) model with java programming language. By using the simulation program, the fractal aggregation growth process can be displayed dynamically in the form of a three-dimensional (3D) figure. Meanwhile, the related kinetics data of aggregation simulation can be also recorded dynamically. Compared to the traditional programs, the program has better real-time performance and is more helpful to observe the fractal growth process, which contributes to the scientific study in fractal aggregation. Besides, because of adopting java programming language, the program has very good cross-platform performance.
Applications of Wavelets in 3-D Audio Simulation
无
2000-01-01
Wavelet has been used as a powerful tool in the signal processing and function approx imation recently. This paper presents the application of wavelets for solving two key problems in 3-1 audio simulation. First, we employ discrete wavelet transform (DWT) combined with vector quantisation (VQ) to compress audio data in order to reduce tremendous redundant data storage and transmission times. Secondly, we use wavelets as the activation functions in neural networks called feed-forward wavelet networks to approach auditory localisation information cues (head-related transfer functions (HRTFs) are used here). The experimental results demonstrate that the applica tion of wavelets is more efficientand useful in 3-D audio simulation.
3D simulation of plant and living tissue superficial lesions
Bratchenko, Ivan A.; Sindyaeva, Alexandra R.; Zakharov, Valery P.
2008-06-01
The analytic schemes of calculated absorbed and scattered radiation spatial distribution in multilayer plant and living tissues and diagnostic of their physical state are presented. The correct realization of these tasks was obtained with 3D Monte Carlo simulation of optical radiation propagation through multiple scattering medium in TracePro environment. Analysis of simulation data was made by differential backscattering method, which allows to investigate general backscattered radiation dependences on optical and geometrical parameters of living tissue. It was shown that obtained results formed the basis for developing an algorithm of optical superficial inhomogeneous registration and spatial localization. Such diagnosis can be executed in tissues of any arbitrary surface structure. Designed scheme is intended to utilize in contactless macro diagnostics device. The same approach was used for simulation of optical spectra of healthy and diseased virtual leaves for plant tissue pathological changes revealing.
Simulation of current generation in a 3-D plasma model
Two wires carrying current in the same direction will attract each other, and two wires carrying current in the opposite direction will repel each other. Now, consider a test charge in a plasma. If the test charge carries current parallel to the plasma, then it will be pulled toward the plasma core, and if the test charge carries current anti-parallel to the plasma, then it will be pushed to the edge. The electromagnetic coupling between the plasma and a test charge (i.e., the Aparallel circ vparallel term in the test charge's Hamiltonian) breaks the symmetry in the parallel direction, and gives rise to a diffusion coefficient which is dependent on the particle's parallel velocity. This is the basis for the open-quotes preferential lossclose quotes mechanism described in the work by Nunan et al. In our previous 2+1/2 D work, in both cylindrical and toroidal geometries, showed that if the plasma column is centrally fueled, then an initial current increases steadily. The results in straight, cylindrical plasmas showed that self generated parallel current arises without trapped particle or neoclassical diffusion, as assumed by the bootstrap theory. It suggests that the fundamental mechanism seems to be the conservation of particles canonical momenta in the direction of the ignorable coordinate. We have extended the simulation to 3D to verify the model put forth. A scalable 3D EM-PIC code, with a localized field-solver, has been implemented to run on a large class of parallel computers. On the 512-node SP2 at Cornell Theory Center, we have benchmarked the 2+1/2 D calculations using 32 grids in the previously ignored direction, and a 100-fold increase in the number of particles. Our preliminary results show good agreements between the 2+1/2 D and the 3D calculations. We will present our 3D results at the meeting
3D TCAD Simulation for Semiconductor Processes, Devices and Optoelectronics
Li, Simon
2012-01-01
Technology computer-aided design, or TCAD, is critical to today’s semiconductor technology and anybody working in this industry needs to know something about TCAD. This book is about how to use computer software to manufacture and test virtually semiconductor devices in 3D. It brings to life the topic of semiconductor device physics, with a hands-on, tutorial approach that de-emphasizes abstract physics and equations and emphasizes real practice and extensive illustrations. Coverage includes a comprehensive library of devices, representing the state of the art technology, such as SuperJunction LDMOS, GaN LED devices, etc. Provides a vivid, internal view of semiconductor devices, through 3D TCAD simulation; Includes comprehensive coverage of TCAD simulations for both optic and electronic devices, from nano-scale to high-voltage high-power devices; Presents material in a hands-on, tutorial fashion so that industry practitioners will find maximum utility; Includes a comprehensive library of devices, re...
3D numerical simulation and analysis of railgun gouging mechanism
Jin-guo Wu
2016-04-01
Full Text Available A gouging phenomenon with a hypervelocity sliding electrical contact in railgun not only shortens the rail lifetime but also affects the interior ballistic performance. In this paper, a 3-D numerical model was introduced to simulate and analyze the generation mechanism and evolution of the rail gouging phenomenon. The results show that a rail surface bulge is an important factor to induce gouging. High density and high pressure material flow on the contact surface, obliquely extruded into the rail when accelerating the armature to a high velocity, can produce gouging. Both controlling the bulge size to a certain range and selecting suitable materials for rail surface coating will suppress the formation of gouging. The numerical simulation had a good agreement with experiments, which validated the computing model and methodology are reliable.
Coniferous Canopy BRF Simulation Based on 3-D Realistic Scene
Wang, Xin-yun; Guo, Zhi-feng; Qin, Wen-han; Sun, Guo-qing
2011-01-01
It is difficulties for the computer simulation method to study radiation regime at large-scale. Simplified coniferous model was investigate d in the present study. It makes the computer simulation methods such as L-systems and radiosity-graphics combined method (RGM) more powerf ul in remote sensing of heterogeneous coniferous forests over a large -scale region. L-systems is applied to render 3-D coniferous forest scenarios: and RGM model was used to calculate BRF (bidirectional refle ctance factor) in visible and near-infrared regions. Results in this study show that in most cases both agreed well. Meanwhiie at a tree and forest level. the results are also good.
Optimizing prostate needle biopsy through 3D simulation
Zeng, Jianchao; Kaplan, Charles; Xuan, Jian Hua; Sesterhenn, Isabell A.; Lynch, John H.; Freedman, Matthew T.; Mun, Seong K.
1998-06-01
Prostate needle biopsy is used for the detection of prostate cancer. The protocol of needle biopsy that is currently routinely used in the clinical environment is the systematic sextant technique, which defines six symmetric locations on the prostate surface for needle insertion. However, this protocol has been developed based on the long-term observation and experience of urologists. Little quantitative or scientific evidence supports the use of this biopsy technique. In this research, we aim at developing a statistically optimized new prostate needle biopsy protocol to improve the quality of diagnosis of prostate cancer. This new protocol will be developed by using a three-dimensional (3-D) computer- based probability map of prostate cancer. For this purpose, we have developed a computer-based 3-D visualization and simulation system with prostate models constructed from the digitized prostate specimens, in which the process of prostate needle biopsy can be simulated automatically by the computer. In this paper, we first develop an interactive biopsy simulation mode in the system, and evaluate the performance of the automatic biopsy simulation with the sextant biopsy protocol by comparing the results by the urologist using the interactive simulation mode with respect to 53 prostate models. This is required to confirm that the automatic simulation is accurate and reliable enough for the simulation with respect to a large number of prostate models. Then we compare the performance of the existing protocols using the automatic biopsy simulation system with respect to 107 prostate models, which will statistically identify if one protocol is better than another. Since the estimation of tumor volume is extremely important in determining the significance of a tumor and in deciding appropriate treatment methods, we further investigate correlation between the tumor volume and the positive core volume with 89 prostate models. This is done in order to develop a method to
Maciej H Swat
Full Text Available Tumor cells and structure both evolve due to heritable variation of cell behaviors and selection over periods of weeks to years (somatic evolution. Micro-environmental factors exert selection pressures on tumor-cell behaviors, which influence both the rate and direction of evolution of specific behaviors, especially the development of tumor-cell aggression and resistance to chemotherapies. In this paper, we present, step-by-step, the development of a multi-cell, virtual-tissue model of tumor somatic evolution, simulated using the open-source CompuCell3D modeling environment. Our model includes essential cell behaviors, microenvironmental components and their interactions. Our model provides a platform for exploring selection pressures leading to the evolution of tumor-cell aggression, showing that emergent stratification into regions with different cell survival rates drives the evolution of less cohesive cells with lower levels of cadherins and higher levels of integrins. Such reduced cohesivity is a key hallmark in the progression of many types of solid tumors.
Simulated Photoevaporative Mass Loss from Hot Jupiters in 3D
Tripathi, Anjali; Kratter, Kaitlin M.; Murray-Clay, Ruth A.; Krumholz, Mark R.
2015-08-01
Ionizing stellar photons heat the upper regions of planetary atmospheres, driving atmospheric mass loss. Gas escaping from several hot, hydrogen-rich planets has been detected using UV and X-ray transmission spectroscopy. Because these planets are tidally locked, and thus asymmetrically irradiated, escaping gas is unlikely to be spherically symmetric. In this paper, we focus on the effects of asymmetric heating on local outflow structure. We use the Athena code for hydrodynamics to produce 3D simulations of hot Jupiter mass loss that jointly model wind launching and stellar heating via photoionization. Our fiducial planet is an inflated, hot Jupiter with radius {R}{{p}}=2.14{R}{Jup} and mass {M}{{p}}=0.53{M}{Jup}. We irradiate the initially neutral, atomic hydrogen atmosphere with 13.6 eV photons and compute the outflow’s ionization structure. There are clear asymmetries in the atmospheric outflow, including a neutral shadow on the planet’s nightside. Given an incident ionizing UV flux comparable to that of the Sun, we find a steady-state mass loss rate of ˜ 2× {10}10 g s-1. The total mass loss rate and the outflow substructure along the substellar ray show good agreement with earlier 1D models, for two different fluxes. Our 3D data cube can be used to generate the outflow’s extinction spectrum during transit. As a proof of concept, we find absorption of stellar Lyα at Doppler-shifted velocities of up to ±50 km s-1. Our work provides a starting point for further 3D models that can be used to predict observable signatures of hot Jupiter mass loss.
Study, simulation and design of a 3D clinostat
Pavone, Valentina; Guarnieri, Vincenzo; Lobascio, Cesare; Soma, Aurelio; Bosso, Nicola; Lamantea, Matteo Maria
High cost and limited number of physically executable experiments in space have introduced the need for ground simulation systems that enable preparing experiments to be carried out on board, identifying phenomena associated with the altered gravity conditions, and taking advantage of these conditions, as in Biotechnology. Among systems developed to simulate microgravity, especially for life sciences experiments, different types of clinostats were realized. This work deals with mechanical design of a three-dimensional clinostat and simulation of the dynamic behavior of the system by varying the operating parameters. The design and simulation phase was preceded by a careful analysis of the state of art and by the review of the most recent results, in particular from the major investigators of Life Sciences in Space. The mechanical design is quite innovative by adoption of a structure entirely in aluminum, which allows robustness while reducing the overall weight. The transmission system of motion has been optimized by means of brushless DC micro motors, light and compact, which helped to reduce weight, dimensions, power consumption and increase the reliability and durability of the system. The study of the dynamic behavior using SIMPACK, a multibody simulation software, led to results in line with those found in the most important and recent scientific publications. This model was also appropriately configured to represent any desired operating condition, and for eventual system scalability. It would be interesting to generate simulated hypogravity - e.g.: 0.38-g (Mars) or 0.17-g (Moon). This would allow to investigate how terrestrial life forms can grow in other planetary habitats, or to determine the gravity threshold response of different organisms. At the moment, such a system can only be achieved by centrifuges in real microgravity. We are confident that simulation and associated tests with our 3D clinostat can help adjusting the parameters allowing variable g
Parallel FEM simulation of 3-D crack propagation
Full text: Crack propagation simulation is an important topic in many fields, e.g., aeronautical engineering, material sciences, and geophysics. This type of simulation requires a high computational power, mainly at three-dimensional mesh generation and structural analysis steps. These steps usually spend a large amount of computing time and machine resources. The main objective of this work is to provide a fast and accurate system for crack growth simulation in three-dimensional models. The main idea of the methodology presented is to parallelize mesh generation and structural analysis procedures, and to integrate these procedures into a computational environment able to perform automatic arbitrary crack propagation. A parallel mesh generation algorithm has been developed. This algorithm is capable of generating three-dimensional meshes of tetrahedral elements in arbitrary domains with one or multiple embedded cracks. A finite element method program called FEMOOP has been adapted to implement the parallel features. The parallel strategy to solve the set of linear equations is based on an element-by-element scheme in conjunction with a gradient iterative solution. A program called FRANC3D, which is completely integrated with other components of the system, performs crack propagation and geometry updates. The entire system is described in details and a set of parallel simulations of crack propagation are presented to show the reliability of the system. Refs. 4 (author)
3D Simulation Modeling of the Tooth Wear Process.
Ning Dai
Full Text Available Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation.
Simulations of drift waves in 3D magnetic configurations
Drift waves are commonly held responsible for anomalous transport in tokamak configurations and in particular for the anomalously high heat loss. The next generation of stellarators on the other hand are hoped to be characterized by a much smaller neo-classical transport and by particle confinement close to that of tokamaks. There is nevertheless a strong interest in the stellarator community to study the properties of drift waves in 3D magnetic configurations. To serve this interest we have developed the first global gyrokinetic code, EUTERPE, aimed at the investigation of linear drift wave stability in general toroidal geometry. The physical model assumes electrostatic waves and adiabatic electrons. EUTERPE is a particle-in-cell (PIC) code in which the gyrokinetic Poisson equation is discretized with the finite element method defined in the PEST -1 system of magnetic coordinates. The magnetic geometry is provided by the magnetohydrodynamic (MHD) equilibrium code VMEC. The complete 3D model has been successfully validated in toroidal axisymmetric and straight helical geometries and has permitted the first simulation of unstable global ITG driven modes in non-axisymmetric toroidal configurations. As a first application, two configurations have been studied, the Quasi-Axially symmetric Stellarator with three fields periods (QAS3) currently one system under consideration at the Princeton Plasma Physics Laboratory and the Helically Symmetric experiment (HSX) which has recently started operation at the University of Wisconsin. QAS3 is characterized by a tokamak-Iike field in the outer part of the torus. In this structure the drift waves are mainly affected by the magnetic shear and barely by the shape of the plasma. Also, the results are very close to those obtained for a tokamak. On the other hand, results for the HSX configuration, which is characterized by a dominant helical magnetic field, show a clear 3D effect, namely a strong toroidal variation of the drift wave
Linking 1D Stellar Evolution to 3D Hydrodynamical Simulations
Cristini, Andrea; Georgy, Cyril; Meakin, Casey; Arnett, David; Viallet, Maxime
2014-01-01
In this contribution we present initial results of a study on convective boundary mixing (CBM) in massive stellar models using the GENEVA stellar evolution code. Before undertaking costly 3D hydrodynamic simulations, it is important to study the general properties of convective boundaries, such as the: composition jump; pressure gradient; and `stiffness'. Models for a 15Mo star were computed. We found that for convective shells above the core, the lower (in radius or mass) boundaries are `stiffer' according to the bulk Richardson number than the relative upper (Schwarzschild) boundaries. Thus, we expect reduced CBM at the lower boundaries in comparison to the upper. This has implications on flame front propagation and the onset of novae.
3D Dynamic Earthquake Fracture Simulation (Test Case)
Korkusuz Öztürk, Yasemin; Meral Özel, Nurcan; Ando, Ryosuke
2016-04-01
A 3D dynamic earthquake fracture simulation is being developed for the fault structures which are non-planar to understand heterogeneous stress states in the Marmara Sea. Locating in a seismic gap, a large earthquake is expected in the center of the Sea of Marmara. Concerning the fact that more than 14 million inhabitants of İstanbul, located very closely to the Marmara Sea, the importance of the analysis of the Central Marmara Sea is extremely high. A few 3D dynamic earthquake fracture studies have been already done in the Sea of Marmara for pure right lateral strike-slip stress regimes (Oglesby and Mai, 2012; Aochi and Ulrich, 2015). In this study, a 3D dynamic earthquake fracture model with heterogeneous stress patches from the TPV5, a SCEC code validation case, is adapted. In this test model, the fault and the ground surfaces are gridded by a scalene triangulation technique using GMSH program. For a grid size changing between 0.616 km and 1.050 km the number of elements for the fault surface is 1984 and for the ground surface is 1216. When these results are compared with Kaneko's results for TPV5 from SPECFEM3D, reliable findings could be observed for the first 6.5 seconds (stations on the fault) although a stability problem is encountered after this time threshold. To solve this problem grid sizes are made smaller, so the number of elements increase 7986 for the fault surface and 4867 for the ground surface. On the other hand, computational problems arise in that case, since the computation time is directly proportional to the number of total elements and the required memory also increases with the square of that. Therefore, it is expected that this method can be adapted for less coarse grid cases, regarding the main difficulty coming from the necessity of an effective supercomputer and run time limitations. The main objective of this research is to obtain 3D dynamic earthquake rupture scenarios, concerning not only planar and non-planar faults but also
3D mapping and simulation of Geneva Lake environmental data
Villard, Roch; Maignan, Michel; Kanevski, Mikhail; Rapin, Francois; Klein, Audrey
2010-05-01
The Geneva Lake is the biggest alpine and subalpine lake in central Europe. The depth of this lake is 309 meters and its total volume of water is 89 billions m3. It takes, on average, around twelve years so that waters of the lake are completely brewed. Furthermore the Geneva lake waters are rich in dissolved substances as carbonate, sulfate. The quantity of particles in suspension in the lake, which mainly arrived from the Rhône, is nowadays around height million of tones. The International Commission for the Leman Lake (CIPEL) works about the improvement of the quality of this lake since 1962. In the present study three dimensional environmental data (temperature, oxygen and nitrate) which cover the period from 1954 to 2008, for a total of 27'500 cases are investigated. We are interested to study the evolution of the temperature of the lake because there is an impact on the reproduction of fishes and also because the winter brewing of the water makes the re-oxygenation of deep-water. In order that biological balance is maintained in a lake, there must be enough oxygen in the water. Moreover, we work on nitrate distribution and evolution because contributions in fertilizers cause eutrophication of lake. The data are very numerous when we consider the time series, some of them with more than 300 occurrences, but there are between 2 and 15 data available for spatial cartography. The basic methodology used for the analysis, mapping and simulations of 3D patterns of environmental data is based on geostatistical predictions (family of kriging models) and conditional stochastic simulations. Spatial and temporal variability, 3D monitoring networks changing over time, make this study challenging. An important problem is also to make interpolation/simulations over a long period of time, like ten years. One way used to overcome this problem, consists in using a weighted average of ten variograms during this period. 3D mapping was carried out using environment data for
Virtual environment display for a 3D audio room simulation
Chapin, William L.; Foster, Scott
1992-06-01
Recent developments in virtual 3D audio and synthetic aural environments have produced a complex acoustical room simulation. The acoustical simulation models a room with walls, ceiling, and floor of selected sound reflecting/absorbing characteristics and unlimited independent localizable sound sources. This non-visual acoustic simulation, implemented with 4 audio ConvolvotronsTM by Crystal River Engineering and coupled to the listener with a Poihemus IsotrakTM, tracking the listener's head position and orientation, and stereo headphones returning binaural sound, is quite compelling to most listeners with eyes closed. This immersive effect should be reinforced when properly integrated into a full, multi-sensory virtual environment presentation. This paper discusses the design of an interactive, visual virtual environment, complementing the acoustic model and specified to: 1) allow the listener to freely move about the space, a room of manipulable size, shape, and audio character, while interactively relocating the sound sources; 2) reinforce the listener's feeling of telepresence into the acoustical environment with visual and proprioceptive sensations; 3) enhance the audio with the graphic and interactive components, rather than overwhelm or reduce it; and 4) serve as a research testbed and technology transfer demonstration. The hardware/software design of two demonstration systems, one installed and one portable, are discussed through the development of four iterative configurations. The installed system implements a head-coupled, wide-angle, stereo-optic tracker/viewer and multi-computer simulation control. The portable demonstration system implements a head-mounted wide-angle, stereo-optic display, separate head and pointer electro-magnetic position trackers, a heterogeneous parallel graphics processing system, and object oriented C++ program code.
3-D Relativistic MHD Simulations of Extragalactic Jets
Nishikawa, K.-I.; Koide, S.; Sakai, J.-I.; Frank, J.; Christodoulou, D. M.; Sol, H.; Mutel, R. L.
1997-12-01
We present the numerical simulations of relativistic jets propagating initially oblique to the field lines of a magnetized ambient medium. Our simulations incorporate relativistic MHD in a four-dimensional spacetime and clearly show that (a) relatively weak, oblique fields (at 1/16 of the equipartition value) have only a negligible influence on the propagating jet and they are passively pushed away by the relativistically moving head; (b) oblique fields in equipartition with the ambient plasma provide more resistance and cause bending at the jet head, but the magnitude of this deflection and the associated backflow are small compared to those identified by previous studies with a 2-D slab model. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently during the simulations. The effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure. Applied to relativistic extragalactic jets from blazars, the new results are encouraging since superluminal outflows exhibit bending near their sources and their environments are profoundly magnetized---but observations do not provide support for irregular kinematics such as large-scale vortical motions and pronounced reverse flows near the points of origin.
Plasma environment of Titan: a 3-D hybrid simulation study
S. Simon
2006-05-01
Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.
3-D MHD Numerical Simulations of Cloud-Wind Interactions
Gregori, G; Ryu, D; Jones, T W; Miniati, Francesco; Ryu, Dongsu
2000-01-01
We present results from three-dimensional (3-D) numerical simulations investigating the magnetohydrodynamics of cloud-wind interactions. The initial cloud is spherical while the magnetic field is uniform and transverse to the cloud motion. A simplified analytical model that describes the magnetic energy evolution in front of the cloud is developed and compared with simulation results. In addition, it is found the interaction of the cloud with a magnetized interstellar medium (ISM) results in the formation of a highly structured magnetotail. The magnetic flux in the wake of the cloud organizes into flux ropes and a reconnection, current sheet is developed, as field lines of opposite polarity are brought close together near the symmetry axis. At the same time, magnetic pressure is strongly enhanced at the leading edge of the cloud from the stretching of the field lines that occurs there. This has an important dynamical effect on the subsequent evolution of the cloud, since some unstable modes tend to be strongl...
3-D NUMERICAL SIMULATIONS OF FLOW LOSS IN HELICAL CHANNEL
ZHAO Ling-zhi; PENG Yan; LU Fang; LI Jian; LI Ran; LIU Bao-lin
2012-01-01
The flow loss of a helical channel Magnetohydrodynamic (MHD) thruster without MHD effect was numerically studied with 3-D simulations,and a flow loss coefficient ξ was defined to quantify the flow loss and its influencing factors were studied.The results show that ξ decreases in a first-order exponential manner with the pitch of a helical wall and the Reynolds number,and it declines slowly when t / T ＞ 0.2 and Re ＞ 105,a flow guide makes the flow more smooth and uniform,especially in the flow guide and helical wall sub-regions and thus reduces the flow loss greatly,by about 30％ with the averaged value of ξ from 0.0385to 0.027,a rectifier weakens the helical flow and strengthens the axial one in the rectifier and outlet sub-regions,thus reduces the rotational kinetic pressure with the averaged value of ξ declining about 4％ from 0.0385 to 0.037,and ξ decreases with a rectifier's axial length when Re ＞ 105.
Simulations of soluble surfactants in 3D multiphase flow
Muradoglu, Metin; Tryggvason, Gretar
2014-10-01
A finite-difference/front-tracking method is developed for simulations of soluble surfactants in 3D multiphase flows. The interfacial and bulk surfactant concentration evolution equations are solved fully coupled with the incompressible Navier-Stokes equations. A non-linear equation of state is used to relate interfacial surface tension to surfactant concentration at the interface. Simple test cases are designed to validate different parts of the numerical algorithm and the computational results are found to be in a good agreement with the analytical solutions. The numerical algorithm is parallelized using a domain-decomposition method. It is then applied to study the effects of soluble surfactants on the motion of buoyancy-driven bubbles in a straight square channel in nearly undeformable (spherical) and deformable (ellipsoidal) regimes. Finally the method is used to examine the effects of soluble surfactants on the lateral migration of bubbles in a pressure-driven channel flow. It is found that surfactant-induced Marangoni stresses counteract the shear-induced lift force and can reverse the lateral bubble migration completely, i.e., the contaminated bubble drifts away from the channel wall and stabilizes at the center of the channel when the surfactant-induced Marangoni stresses are sufficiently large.
Simulated Photoevaporative Mass Loss from Hot Jupiters in 3D
Tripathi, Anjali; Murray-Clay, Ruth A; Krumholz, Mark R
2015-01-01
Ionizing stellar photons heat the upper regions of planetary atmospheres, driving atmospheric mass loss. Gas escaping from several hot, hydrogen-rich planets has been detected using UV and X-ray transmission spectroscopy. Because these planets are tidally locked, and thus asymmetrically irradiated, escaping gas is unlikely to be spherically symmetric. In this paper, we focus on the effects of asymmetric heating on local outflow structure. We use the Athena code for hydrodynamics to produce 3D simulations of hot Jupiter mass loss that jointly model wind launching and stellar heating via photoionization. Our fiducial planet is an inflated, hot Jupiter with radius $R_p=2.14 R_{\\rm Jup}$ and mass $M_p = 0.53 M_{\\rm Jup}$. We irradiate the initially neutral, atomic hydrogen atmosphere with 13.6 eV photons and compute the outflow's ionization structure. There are clear asymmetries in the atmospheric outflow, including a neutral shadow on the planet's nightside. Given an incident ionizing UV flux comparable to that ...
3-D simulation of posterior fossa reduction in Chiari I
Yvens Barbosa Fernandes
2016-05-01
Full Text Available ABSTRACT We proposed a 3D model to evaluate the role of platybasia and clivus length in the development of Chiari I (CI. Using a computer aided design software, two DICOM files of a normal CT scan and MR were used to simulate different clivus lengths (CL and also different basal angles (BA. The final posterior fossa volume (PFV was obtained for each variation and the percentage of the volumetric change was acquired with the same method. The initial normal values of CL and BA were 35.65 mm and 112.66º respectively, with a total PFV of 209 ml. Ranging the CL from 34.65 to 29.65 – 24.65 – 19.65, there was a PFV decrease of 0.47% – 1.12% – 1.69%, respectively. Ranging the BA from 122.66º to 127.66º – 142.66º, the PFV decreased 0.69% – 3.23%, respectively. Our model highlights the importance of the basal angle and clivus length to the development of CI.
3-D simulation of posterior fossa reduction in Chiari I.
Fernandes, Yvens Barbosa; Perestrelo, Pedro Fábio Mendonça; Noritomi, Pedro Yoshito; Mathias, Roger Neves; Silva, Jorge Vicente Lopes da; Joaquim, Andrei Fernandes
2016-05-01
We proposed a 3D model to evaluate the role of platybasia and clivus length in the development of Chiari I (CI). Using a computer aided design software, two DICOM files of a normal CT scan and MR were used to simulate different clivus lengths (CL) and also different basal angles (BA). The final posterior fossa volume (PFV) was obtained for each variation and the percentage of the volumetric change was acquired with the same method. The initial normal values of CL and BA were 35.65 mm and 112.66º respectively, with a total PFV of 209 ml. Ranging the CL from 34.65 to 29.65 - 24.65 - 19.65, there was a PFV decrease of 0.47% - 1.12% - 1.69%, respectively. Ranging the BA from 122.66º to 127.66º - 142.66º, the PFV decreased 0.69% - 3.23%, respectively. Our model highlights the importance of the basal angle and clivus length to the development of CI. PMID:27191237
Transient simulations in WWER-1000-comparison between DYN3D-ATHLET and DYN3D-RELAP5
Simulations of a real transient of an operating WWER-1000 power plant have been performed using DYN3D-ATHLET (Gru95) and DYN3D-RELAP5 (Koy01) code systems in the frame of activities aimed at a validation of the neutronic / thermal-hydraulic coupled codes. The transient initiated by a main coolant pump switching off, when three of the four main coolant pumps of the plant are in operation (scenario of the VALCO project) is chosen for the simulation. The same models of the plant (except the core nodalization) but two different libraries of macroscopic cross-sections have been used in compared calculations. Additionally, the compared code systems are based on the different / external and internal / coupling techniques. This paper contains a brief description of the coupled codes and the plant model as well as a comparison between the results from simulations (Authors)
3D simulation studies of tokamak plasmas using MHD and extended-MHD models
The M3D (Multi-level 3D) tokamak simulation project aims at the simulation of tokamak plasmas using a multi-level tokamak code package. Several current applications using MHD and Extended-MHD models are presented; high-β disruption studies in reversed shear plasmas using the MHD level MH3D code, ω*i stabilization and nonlinear island saturation of TAE mode using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree which agree well with experimental data
Interdisciplinary Collaboration through Designing 3D Simulation Case Studies
Bai, Xin; 10.5121/ijma.2011.3109
2011-01-01
Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs, and conduct cross-discipline research for effective learning. Based upon the scripts designed by faculty from five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.
Interdisciplinary Collaboration through Designing 3D Simulation Case Studies
Xin Bai
2011-02-01
Full Text Available Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs, and conduct cross-discipline research for effective learning. Based upon the scripts designed by faculty from five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.
Interdisciplinary Collaboration through Designing 3D Simulation Case Studies
Xin Bai
2011-02-01
Full Text Available Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs,and conduct cross-discipline research for effective learning. Based upon the scripts designed by facultyfrom five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.
Towards the 3D Web with Open Simulator
Oliver, Iain Angus; Miller, Alan Henry David; Allison, Colin; Kennedy, Sarah Elizabeth; Dow, Lisa; Campbell, Anne; Davies, Christopher John; McCaffery, John Philip
2013-01-01
Continuing advances and reduced costs in computational power, graphics processors and network bandwidth have led to 3D immersive multi-user virtual worlds becoming increasingly accessible while offering an improved and engaging Quality of Experience. At the same time the functionality of the World Wide Web continues to expand alongside the computing infrastructure it runs on and pages can now routinely accommodate many forms of interactive multimedia components as standard features - streamin...
3D interactive visualization of crowd simulations at urban scale
Fanini, Bruno; Calori, Luigi
2014-01-01
Digital representations of the urban environment have constantly increased their complexity: starting from fixed chunks of 2D segment depicting the building base to complex data-sets comprising several layer of information such as multi-resolution GIS data combined with on field 3D data acquisition. Cities in particular and urban development in general emerge from the bottom up, so crowd is an essential part of the city environment but it is often absent from most of the intera...
DREAM3D simulations of inner-belt dynamics
Cunningham, Gregory Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-05-26
A 1973 paper by Lyons and Thorne explains the two-belt structure for electrons in the inner magnetosphere as a balance between inward radial diffusion and loss to the atmosphere, where the loss to the atmosphere is enabled by pitch-angle scattering from Coulomb and wave-particle interactions. In the 1973 paper, equilibrium solutions to a decoupled set of 1D radial diffusion equations, one for each value of the first invariant of motion, μ, were computed to produce the equilibrium two-belt structure. Each 1D radial diffusion equation incorporated an L-and μ-dependent `lifetime' due to the Coulomb and wave-particle interactions. This decoupling of the problem is appropriate under the assumption that radial diffusion is slow in comparison to pitch-angle scattering. However, for some values of μ and L the lifetime associated with pitch-angle scattering is comparable to the timescale associated with radial diffusion, suggesting that the true equilibrium solutions might reflect `coupled modes' involving pitch-angle scattering and radial diffusion and thus requiring a 3D diffusion model. In the work we show here, we have computed the equilibrium solutions using our 3D diffusion model, DREAM3D, that allows for such coupling. We find that the 3D equilibrium solutions are quite similar to the solutions shown in the 1973 paper when we use the same physical models for radial diffusion and pitch-angle scattering from hiss. However, we show that the equilibrium solutions are quite sensitive to various aspects of the physics model employed in the 1973 paper that can be improved, suggesting that additional work needs to be done to understand the two-belt structure.
Using 3-D Numerical Weather Data in Piloted Simulations
Daniels, Taumi S.
2016-01-01
This report describes the process of acquiring and using 3-D numerical model weather data sets in NASA Langley's Research Flight Deck (RFD). A set of software tools implement the process and can be used for other purposes as well. Given time and location information of a weather phenomenon of interest, the user can download associated numerical weather model data. These data are created by the National Oceanic and Atmospheric Administration (NOAA) High Resolution Rapid Refresh (HRRR) model, and are then processed using a set of Mathworks' Matlab(TradeMark) scripts to create the usable 3-D weather data sets. Each data set includes radar re ectivity, water vapor, component winds, temperature, supercooled liquid water, turbulence, pressure, altitude, land elevation, relative humidity, and water phases. An open-source data processing program, wgrib2, is available from NOAA online, and is used along with Matlab scripts. These scripts are described with sucient detail to make future modi cations. These software tools have been used to generate 3-D weather data for various RFD experiments.
3d particle simulations on ultra short laser interaction
Nishihara, Katsunobu; Okamoto, Takashi; Yasui, Hidekazu [Osaka Univ., Suita (Japan). Inst. of Laser Engineering
1998-03-01
Two topics related to ultra short laser interaction with matter, linear and nonlinear high frequency conductivity of a solid density hydrogen plasma and anisotropic self-focusing of an intense laser in an overdense plasma, have been investigated with the use of 3-d particle codes. Frequency dependence of linear conductivity in a dense plasma is obtained, which shows anomalous conductivity near plasma frequency. Since nonlinear conductivity decreases with v{sub o}{sup -3}, where v{sub o} is a quivering velocity, an optimum amplitude exists leading to a maximum electron heating. Anisotropic self-focusing of a linear polarized intense laser is observed in an overdense plasma. (author)
Mesh Resolution Effect on 3D RANS Turbomachinery Flow Simulations
Yershov, Sergiy
2016-01-01
The paper presents the study of the effect of a mesh refinement on numerical results of 3D RANS computations of turbomachinery flows. The CFD solver F, which based on the second-order accurate ENO scheme, is used in this study. The simplified multigrid algorithm and local time stepping permit decreasing computational time. The flow computations are performed for a number of turbine and compressor cascades and stages. In all flow cases, the successively refined meshes of H-type with an approximate orthogonalization near the solid walls were generated. The results obtained are compared in order to estimate their both mesh convergence and ability to resolve the transonic flow pattern. It is concluded that for thorough studying the fine phenomena of the 3D turbomachinery flows, it makes sense to use the computational meshes with the number of cells from several millions up to several hundred millions per a single turbomachinery blade channel, while for industrial computations, a mesh of about or less than one mil...
3D Hydrodynamic Simulations of Relativistic Extragalactic Jets
Hughes, P A; Duncan, G C; Hughes, Philip A.; Miller, Mark A.
2002-01-01
We describe a new numerical 3D relativistic hydrodynamical code, the results of validation tests, and a comparison with earlier, 2D studies. The 3D code has been used to study the deflection and precession of relativistic flows. We find that even quite fast jets (gamma~10) can be significantly influenced by impinging on an oblique density gradient, exhibiting a rotation of the Mach disk in the jet's head. The flow is bent via a potentially strong, oblique internal shock that arises due to asymmetric perturbation of the flow by its cocoon. In extreme cases this cocoon can form a marginally relativistic flow orthogonal to the jet, leading to large scale dynamics quite unlike that normally associated with astrophysical jets. Exploration of a gamma=5 flow subject to a large amplitude precession (semi-angle 11.25dg) shows that it retains its integrity, with modest reduction in Lorentz factor and momentum flux, for almost 50 jet-radii, but thereafter, the collimated flow is disrupted. The flow is approximately ball...
3D Numerical Simulation of Projectile Penetration into Concrete Target
无
2008-01-01
Basing on the explicit instantaneous dynamics software MSC-Dytran and the general coupling arithmetic, the process of the projectile penetration into concrete target was simulated with the point-line-surface-body modeling method. Simulation results are in agreement with experimental results. The simulated data could provide design reference for the defense engineering construction and penetrator design.
Parallel Simulation of 3-D Turbulent Flow Through Hydraulic Machinery
徐宇; 吴玉林
2003-01-01
Parallel calculational methods were used to analyze incompressible turbulent flow through hydraulic machinery. Two parallel methods were used to simulate the complex flow field. The space decomposition method divides the computational domain into several sub-ranges. Parallel discrete event simulation divides the whole task into several parts according to their functions. The simulation results were compared with the serial simulation results and particle image velocimetry (PIV) experimental results. The results give the distribution and configuration of the complex vortices and illustrate the effectiveness of the parallel algorithms for numerical simulation of turbulent flows.
Single-sided sheet-to-tube spot welding investigated by 3D numerical simulations
Nielsen, Chris Valentin; Chergui, Azeddine; Zhang, Wenqi
The single-sided resistance spot welding process is analyzed by a 3D numerical study of sheet-to-tube joining. Finite element simulations are carried out in SORPAS® 3D. Two levels of electrode force and five levels of welding current are simulated. The overall effects of changing current and forc...
3D simulation studies of tokamak plasmas using MHD and extended-MHD models
The M3D (Multi-level 3D) tokamak simulation project aims at the simulation of tokamak plasmas using a multi-level tokamak code package. Several current applications using MHD and Extended-MHD models are presented; high-β disruption studies in reversed shear plasmas using the MHD level MH3D code, ω*i stabilization and nonlinear island rotation studies using the two-fluid level MH3D-T code, studies of nonlinear saturation of TAE modes using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree well with experimental data
3D simulation studies of tokamak plasmas using MHD and extended-MHD models
The M3D (Multi-level 3D) tokamak simulation project aims at the simulation of tokamak plasmas using a multi-level tokamak code package. Several current applications using MHD and Extended-MHD models are presented: high-β disruption studies in reversed shear plasmas using the MHD level MH3D code; ω*i stabilization and nonlinear island rotation studies using the two-fluid level MH3D-T code; studies of nonlinear saturation of TAE modes using the hybrid particle/MHD level MH3D-K code; and unstructured mesh MH3D++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree well with experimental data. (author). 18 refs, 5 figs
Simulations of RUTA-70 reactor with CERMET fuel using DYN3D/ATHLET and DYN3D/RELAP5 coupled codes
RUTA-70 model for simulations with the internally coupled codes DYN3D/ATHLET and DYN3D/RELAP5 was developed. A 3-D power distribution in the core is calculated by DYN3D with thermal-hydraulic feedback from the system codes. A steady-state corresponding to the full reactor power and an accident scenario initiated by failure of all primary coolant pumps were simulated with the DYN3D/ATHLET and DYN3D/RELAP5 coupled code systems to verify these codes. The compared coupled codes give close predictions for the initial and final states of the simulated accident but not for the transition between them. The observed deviations are explained by differences in the subcooled boiling models of the employed versions of ATHLET and RELAP5. Nevertheless, both simulations confirm a high level of the reactor inherent safety. The allowed safety margins were not reached. (orig.)
Simulations of RUTA-70 reactor with CERMET fuel using DYN3D/ATHLET and DYN3D/RELAP5 coupled codes
Kozmenkov, Y.; Rohde, U. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) e.V., Dresden (Germany); Baranaev, Y.; Glebov, A. [State Scientific Center of the Russian Federation, Obninsk, Kaluga Region (Russian Federation). Inst. for Physics and Power Engineering
2012-08-15
RUTA-70 model for simulations with the internally coupled codes DYN3D/ATHLET and DYN3D/RELAP5 was developed. A 3-D power distribution in the core is calculated by DYN3D with thermal-hydraulic feedback from the system codes. A steady-state corresponding to the full reactor power and an accident scenario initiated by failure of all primary coolant pumps were simulated with the DYN3D/ATHLET and DYN3D/RELAP5 coupled code systems to verify these codes. The compared coupled codes give close predictions for the initial and final states of the simulated accident but not for the transition between them. The observed deviations are explained by differences in the subcooled boiling models of the employed versions of ATHLET and RELAP5. Nevertheless, both simulations confirm a high level of the reactor inherent safety. The allowed safety margins were not reached. (orig.)
Fault interpretation strategy for 3D model simulation
Mendoza, P.; Floricich, M. [Petroleos de Venezuela SA EPM, Caracas (Venezuela)
2002-07-01
A 3-dimensional cellular model and visualization software was developed to help characterize the spatial geometry of a petroleum reservoir in order to determine the distribution of the petrophysical properties in a coherent manner. The 3-D analysis requires the same input data as traditional 2-dimensional methods so it is not more expensive, but it improves the integrity of geologic interpretations. The model makes it possible to generate fault planes which contribute to the understanding of the structural configuration of a petroleum deposit. Visualization tools provide quality control and are used to verify grid geometry in faulted structures and fault planes. The authors present experiences gained in building the geologic model for the LL-03 reservoir in Venezuela's Lake Maracaibo region which forms part of the Bolivar Coastal Field. The reservoir has more than 2,000 well that penetrate its vertical section, of which 1051 have been completed and which make up 30 per cent of the total production of the La Rosa Medium segregation of the Maracaibo District. 5 refs., 17 figs.
3D measurements of buildings and environment for harbor simulators
Börlin, Niclas; Igasto, Christina
2009-01-01
Oryx Simulations develops and manufactures real-time physics simulators for training of harbor crane operator in several of the world’s major harbors. Currently, the modelling process is labor-intensive and a faster solution that can produce accurate, textured models of harbor scenes is desired. The accuracy requirements vary across the scene, and in some areas accuracy can be traded for speed. Due to the heavy equipment involved, reliable error estimates are important throughout the scene. T...
The advanced simulation of fatigue crack growth in complex 3D structures
Kolk, Karsten; Kuhn, Guenther [Institute of Applied Mechanics, Erlangen (Germany)
2006-12-15
An advanced incremental crack growth algorithm for the three-dimensional (3D) simulation of fatigue crack growth in complex 3D structures with linear elastic material behavior is presented. To perform the crack growth simulation as effectively as possible an accurate stress analysis is done by the boundary-element method (BEM) in terms of the 3D dual BEM. The question concerning a reliable 3D crack growth criterion is answered based on experimental observations. All criteria under consideration are numerically realized by a predictor-corrector procedure. The agreement between numerically determined and experimentally observed crack fronts will be shown on both fracture specimens and an industrial application. (orig.)
3D Simulations of methane convective storms on Titan's atmosphere
Hueso, R.; Sánchez-Lavega, A.
2005-08-01
The arrival of the Cassini/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan imply a saturated atmosphere of methane (amounting perhaps to 150 covered by methane clouds, if we think on Earth meteorology. However, observations from Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Pole (currently in its summer season). This might imply a lack of widespread presence on Titan of nuclei where methane could initiate condensation and particle growth with subsequent precipitation. We investigate different scenarios of moist convective storms on Titan using a complete 3D atmospheric model that incorporates a full microphysics treatment required to study cloud formation processes under a saturated atmosphere with low concentration of condensation nuclei. We study local convective development under a variety of atmospheric conditions: sub-saturation, super-saturation, abundances of condensation nuclei fall, condensation nuclei lifted from the ground or gently falling from the stratosphere. We show that under the appropriate circumstances, precipitation rates comparable to typical tropical storms on Earth can be found. Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges a post-doc fellowship from Gobierno Vasco.
SIERRA - A 3-D device simulator for reliability modeling
Chern, Jue-Hsien; Arledge, Lawrence A., Jr.; Yang, Ping; Maeda, John T.
1989-05-01
SIERRA is a three-dimensional general-purpose semiconductor-device simulation program which serves as a foundation for investigating integrated-circuit (IC) device and reliability issues. This program solves the Poisson and continuity equations in silicon under dc, transient, and small-signal conditions. Executing on a vector/parallel minisupercomputer, SIERRA utilizes a matrix solver which uses an incomplete LU (ILU) preconditioned conjugate gradient square (CGS, BCG) method. The ILU-CGS method provides a good compromise between memory size and convergence rate. The authors have observed a 5x to 7x speedup over standard direct methods in simulations of transient problems containing highly coupled Poisson and continuity equations such as those found in reliability-oriented simulations. The application of SIERRA to parasitic CMOS latchup and dynamic random-access memory single-event-upset studies is described.
Humanoid Robot 3 -D Motion Simulation for Hardware Realization
CAO Xi; ZHAO Qun-fei; MA Pei-sun
2007-01-01
In this paper, three dimensions kinematics andkinetics simulation arc discussed for hardware realization ofa physical biped walking-chair robot. The direct and inverseclose-form kinematics solution of the biped walking-chairis deduced. Several gaits are realized with thekinematics solution, including walking straight on levelfloor, going up stair, squatting down and standing up. ZeroMoment Point(ZMP) equation is analyzed considering themovement of the crew. The simulated biped walking-chairrobot is used for mechanical design, gaits development andvalidation before they are tested on real robot.
Coupled cavity 3-D codes for linac tolerance simulations
Three developing codes, based on previous work at Los Alamos (1) are now being used in the Fermilab Linac Upgrade project, to survey system tolerance requirements. Both linear and non-linear beam dynamics of a pi-mode side coupled 805 MHz linac are simulated. Particular attention to the z-plane synchronism has been integrated into the code group, so that klystron drive boundaries can be monitored in the dynamics. All system length errors that contribute to desynchronization, and other data set failures are recognized by the particle PIC code (CAVDYN) to enhance design coherence. Some current results of the CAVDYN code simulations will be discussed
Hierarchical approach to 'atomistic' 3-D MOSFET simulation
Asenov, A.; Brown, A. R.; J. H. Davies; S Saini
1999-01-01
We present a hierarchical approach to the 'atomistic' simulation of aggressively scaled sub-0.1-Î¼m MOSFETs. These devices are so small that their characteristics depend on the precise location of dopant atoms within them, not just on their average density. A full-scale three-dimensional drift-diffusion atomistic simulation approach is first described and used to verify more economical, but restricted, options. To reduce processor time and memory requirements at high drain voltage, we have de...
Simulation of 3D-CRT treatment for lung cancer
In radiotherapy treatment for lung cancer, occurs doses deposition in healthy organs. During the treatment planning are calculated some doses due to photons. This dose deposition in healthy organs could induce to the appearance of new cancers foci. The aim of this study was to analyze the equivalent doses in healthy organs of a patient treated by radiotherapy for lung cancer. In order to calculate the doses, was done a computer simulation of radiotherapy treatment for lung cancer, adopting database of the treatment performed by INCA. To perform the simulation was used several tools, among them, the radiation transport code MCNPX, in which was shaped the radiotherapy room and the head from the linear accelerator Varian 2300 C / D, the patient was simulated by Voxel male phantom in Rex,and the treatment protocol adopted considers a beam with energy of 6 MV focusing on three gantry tilt angles (0 deg, 180 deg and 45 deg). In addition, there was variation in the opening of the radiation field according to the angle of inclination. The results of this study point to the organs close to the irradiated area are predominantly affected by the dose due to photons, affecting organs from different body systems, such as esophagus, heart, thymus, spine and lymph nodes. The calculated values demonstrating that the angle of 0 deg was the most responsible for the deposit of unwanted dose. The results showed that the simulations in this paper is developed in accordance with the planning data described in different studies and literature. (author)
Microbial Enhanced Oil Recovery: 3D Simulation with Gravity Effects
Nielsen, Sidsel Marie; Jessen, K.; Shapiro, Alexander;
2010-01-01
Microbial enhanced oil recovery (MEOR) utilizes the activity of microorganisms, where microorganisms simultaneously grow in a reservoir and convert substrate into recovery enhancing products (usually, surfactants). In order to predict the performance of a MEOR process, a simulation tool is requir...
Vectors in Use in a 3D Juggling Game Simulation
Kynigos, Chronis; Latsi, Maria
2006-01-01
The new representations enabled by the educational computer game the "Juggler" can place vectors in a central role both for controlling and measuring the behaviours of objects in a virtual environment simulating motion in three-dimensional spaces. The mathematical meanings constructed by 13 year-old students in relation to vectors as objects, as a…
Simulation of 3D-CRT treatment for lung cancer
Thalhofer, Jardel L.; Silva, Ademir X. da; Junior, Juraci R.P., E-mail: jardellt@yahoo.com.br [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Rebello, Wilson F., E-mail: rebello@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Correa, Samanda C.A., E-mail: samandacristine@uezo.rj.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil); Souza, Edmilson M., E-mail: emonteiro@nuclear.ufrj.br [Centro Universitario da Zona Oeste (UEZO), Rio de Janeiro, RJ (Brazil). Colegiado de Comutacao e Matematica; Batista, Delano V.S., E-mail: delano@inca.gov.br [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil)
2013-07-01
In radiotherapy treatment for lung cancer, occurs doses deposition in healthy organs. During the treatment planning are calculated some doses due to photons. This dose deposition in healthy organs could induce to the appearance of new cancers foci. The aim of this study was to analyze the equivalent doses in healthy organs of a patient treated by radiotherapy for lung cancer. In order to calculate the doses, was done a computer simulation of radiotherapy treatment for lung cancer, adopting database of the treatment performed by INCA. To perform the simulation was used several tools, among them, the radiation transport code MCNPX, in which was shaped the radiotherapy room and the head from the linear accelerator Varian 2300 C / D, the patient was simulated by Voxel male phantom in Rex,and the treatment protocol adopted considers a beam with energy of 6 MV focusing on three gantry tilt angles (0 deg, 180 deg and 45 deg). In addition, there was variation in the opening of the radiation field according to the angle of inclination. The results of this study point to the organs close to the irradiated area are predominantly affected by the dose due to photons, affecting organs from different body systems, such as esophagus, heart, thymus, spine and lymph nodes. The calculated values demonstrating that the angle of 0 deg was the most responsible for the deposit of unwanted dose. The results showed that the simulations in this paper is developed in accordance with the planning data described in different studies and literature. (author)
3D simulation of superconducting microwave devices with an electromagnetic-field simulator
Takeuchi, N.; Yamanashi, Yuki; Saito, Y; Yoshikawa, Nobuyuki
2009-01-01
High-frequency microwave applications, such as filters, delay lines, and resonators, are quite important for superconducting electronic devices. In order to design the superconducting microwave devices, circuit parameters should be precisely extracted from the physical structure of the devices. A 3-dimentional electromagnetic-field simulators is very useful for designing microwave devices. However, designing of superconducting microwave devices using a conventional 3D electromagnetic-field si...
Advanced 3D Photocathode Modeling and Simulations Final Report
High brightness electron beams required by the proposed Next Linear Collider demand strong advances in photocathode electron gun performance. Significant improvement in the production of such beams with rf photocathode electron guns is hampered by the lack high-fidelity simulations. The critical missing piece in existing gun codes is a physics-based, detailed treatment of the very complex and highly nonlinear photoemission process
Dynamic triangulations for efficient 3D simulation of granular materials
Ferrez, Jean-Albert; Liebling, Thomas M.
2007-01-01
Granular materials are omnipresent in many fields ranging from civil engineering to food, mining and pharmaceutical industries. Often considered a fourth state of matter, they exhibit specific phenomena such as segregation, arching effects, pattern formation, etc. Due to its potential capability of realistically rendering these behaviors, the Distinct Element Method (DEM) is a very enticing simulation technique. Indeed it makes it possible to analyze and observe phenomena that are barely if a...
3D MHD simulation of polarized emission in SN 1006
Schneiter, E M; Reynoso, E M; Esquivel, A; De Colle, F
2015-01-01
We use three dimensional magnetohydrodynamic (MHD) simulations to model the supernova remnant SN 1006. From our numerical results, we have carried out a polarization study, obtaining synthetic maps of the polarized intensity, the Stokes parameter $Q$, and the polar-referenced angle, which can be compared with observational results. Synthetic maps were computed considering two possible particle acceleration mechanisms: quasi-parallel and quasi-perpendicular. The comparison of synthetic maps of the Stokes parameter $Q$ maps with observations proves to be a valuable tool to discern unambiguously which mechanism is taking place in the remnant of SN 1006, giving strong support to the quasi-parallel model.
Kolk, K.
2005-07-15
This is an important contribution to reliable simulation of stable fatigue crack growth in real 3D problems under complex loads. The nonlinear crack propagation process requires an incremental solution algorithm. Each increment starts with a load analysis of the current crack configuration using the fast dual boundary element method. The potential of this method is more fully utilized with a fast boundary element formulation. Afater this, a real 3D crack propagation criterion is evaluated which is based on experimental findings and is realized within a preditor-corrector method. Finally, the numeric model is generated for the next increment. This generation is made automatically using a local renetworking algorithm. With the crack propagation module thus developed, complex components, e.g. motor car components, can be analyzed fracture-mechanically on a standard PC. (orig.) [German] Die vorliegende Arbeit leistet einen wesentlichen Beitrag zur zuverlaessigen Simulation des stabilen Ermuedungsrisswachstums in realen 3D-Problemen unter komplexen Belastungen. Der nichtlineare Vorgang des Risswachstums erfordert einen inkrementellen Loesungsalgorithmus. In jedem Inkrement wird zunaechst eine Beanspruchungsanalyse der aktuellen Risskonfiguration mit der leistungsstarken dualen Randelementmethode durchgefuehrt. Das Potenzial dieser Methode wird mit einer schnellen Randelementformulierung weiter ausgeschoepft. Anschliessend wird ein echtes 3D-Rissfortschrittskriterium ausgewertet, welches auf experimentellen Erkenntnissen beruht und innerhalb eines Praediktor-Korrektor-Verfahrens realisiert ist. Abschliessend wird das numerische Modell fuer das naechste Inkrement generiert. Diese Generierung erfolgt automatisch mit einem lokalen Neuvernetzungsalgorithmus. Mit dem entwickelten Rissfortschrittsmodul koennen komplexe Bauteile, z.B. aus dem Automobilbau, erfolgreich auf einem Standard-PC bruchmechanisch analysiert werden.
Plasma boundaries at Mars: a 3-D simulation study
A. Bößwetter
2004-12-01
Full Text Available The interaction of the solar wind with the ionosphere of planet Mars is studied using a three-dimensional hybrid model. Mars has only a weak intrinsic magnetic field, and consequently its ionosphere is directly affected by the solar wind. The gyroradii of the solar wind protons are in the range of several hundred kilometers and therefore comparable with the characteristic scales of the interaction region. Different boundaries emerge from the interaction of the solar wind with the continuously produced ionospheric heavy-ion plasma, which could be identified as a bow shock (BS, ion composition boundary (ICB and magnetic pile up boundary (MPB, where the latter both turn out to coincide. The simulation results regarding the shape and position of these boundaries are in good agreement with the measurements made by Phobos-2 and MGS spacecraft. It is shown that the positions of these boundaries depend essentially on the ionospheric production rate, the solar wind ram pressure, and the often unconsidered electron temperature of the ionospheric heavy ion plasma. Other consequences are rays of planetary plasma in the tail and heavy ion plasma clouds, which are stripped off from the dayside ICB region by some instability.
Key words. Magnetospheric physics (solar wind interactions with unmagnetized bodies – Space plasma physics (discontinuities; numerical simulation studies
3D Computational Simulation of Calcium Leaching in Cement Matrices
Gaitero, J. J.
2014-12-01
Full Text Available Calcium leaching is a degradation process consisting in progressive dissolution of the cement paste by migration of calcium atoms to the aggressive solution. It is therefore, a complex phenomenon involving several phases and dissolution and diffusion processes simultaneously. Along this work, a new computational scheme for the simulation of the degradation process in three dimensions was developed and tested. The toolkit was used to simulate accelerated calcium leaching by a 6M ammonium nitrate solution in cement matrices. The obtained outputs were the three dimensional representation of the matrix and the physicochemical properties of individual phases as a consequence of the degradation process. This not only makes it possible to study the evolution of such properties as a function of time but also as a function of the position within the matrix. The obtained results are in good agreement with experimental values of the elastic modulus in degraded and undegraded samples.El lixiviado de calcio es un proceso de degradación consistente en la disolución progresiva de la pasta de cemento por la migración de los átomos de calcio a la disolución agresiva. Se trata por tanto de un fenómeno complejo que involucra simultáneamente diferentes fases y procesos de disolución y difusión. En este trabajo se desarrolló y probó una nueva herramienta computacional para la simulación del proceso de degradación en tres dimensiones. Para ello se simuló el lixiviado de calcio acelerado provocado por una disolución de nitrato amónico 6M en matrices de cemento. Como resultado se obtuvieron la representación tridimensional de la matriz y las propiedades físico-químicas sus fases a lo largo del tiempo. Esto permitió estudiar la evolución de dichas propiedades a lo largo del proceso de degradación así como en función de su posición dentro de la matriz. Los resultados obtenidos coinciden con los valores experimentales del módulo elástico tanto
Simulation of Fully Nonlinear 3-D Numerical Wave Tank
张晓兔; 滕斌; 宁德志
2004-01-01
A fully nonlinear numerical wave tank (NWT) has been simulated by use of a three-dimensional higher order boundary element method (HOBEM) in the time domain. Within the frame of potential flow and the adoption of simply Rankine source, the resulting boundary integral equation is repeatedly solved at each time step and the fully nonlinear free surface boundary conditions are integrated with time to update its position and boundary values. A smooth technique is also adopted in order to eliminate the possible saw-tooth numerical instabilities. The incident wave at the uptank is given as theoretical wave in this paper. The outgoing waves are absorbed inside a damping zone by spatially varying artificial damping on the free surface at the wave tank end. The numerical results show that the NWT developed by these approaches has a high accuracy and good numerical stability.
3-D Coldtest Simulations of W-Band Devices
Petillo, John J.
1998-04-01
Recent advances in the simulation and modeling of vacuum electronic devices has opened up the door for the much-anticipated ``first-pass design success" of these devices by computational means. For W-band, this is an exciting prospect since many current designs begin with scaling from lower-frequency devices. The next step is trial and error by fabrication and experimental testing, which demands high precision machining practices as well as reproducible assembly procedures. This can be a very time-consuming, expensive, and error-prone undertaking. Aside from the unit-to-unit variances in dimensions between prototypes, the repeatability of material properties (e.g., dielectric constant and resistivity) in this frequency band is difficult to measure, predict, and ensure. Computers have no such repeatability problems, and run-to-run differences can be predefined, and subsequently analyzed. The computational limitations include setup difficulty, computer time, computer power, and fidelity of the calculation. For W-band devices with 1% or lower bandwidth, fidelity of the numerical solution is critical in the search for ``first-pass design success" capability. The codes have to not only be up to the task, but the appropriate application of these codes becomes an essential ingredient to predicting the accuracy of the results. These issues as well as cross validation between computational models will be discussed. Several recent simulation results of W-band devices will be presented, along with comparisons with data. These will include the NRL/Litton/CPI gyroklystron input coupler and several CPI Coupled Cavity Tube designs.
Fajardo, Kristel C Meza; Chaillat, Stéphanie; Lenti, Luca
2016-01-01
In this work, we study seismic wave amplification in alluvial basins having 3D standard geometries through the Fast Multipole Boundary Element Method in the frequency domain. We investigate how much 3D amplification differs from the 1D (horizontal layering) case. Considering incident fields of plane harmonic waves, we examine the relationships between the amplification level and the most relevant physical parameters of the problem (impedance contrast, 3D aspect ratio, vertical and oblique incidence of plane waves). The FMBEM results show that the most important parameters for wave amplification are the impedance contrast and the so-called equivalent shape ratio. Using these two parameters, we derive simple rules to compute the fundamental frequency for various 3D basin shapes and the corresponding 3D/1D amplification factor for 5% damping. Effects on amplification due to 3D basin asymmetry are also studied and incorporated in the derived rules.
Product management: visualization technology and 3D simulator of Aker Solutions
Tongpradith, Thanaruch
2014-01-01
This Thesis has focused on Visualization and Simulation Technology in oil and gas industry. It contains the common usages and the implementation process of this new advance technology. 3D Visualization Technology has just been introduced since last decades in Exploration & Production of oilfield development. Aker Solutions has introduced the new innovation technology product solutions, which is 3D simulator software for training, planning and testing purposes in relation to operational projec...
Numerical simulation of 3D backward facing step flows at various Reynolds numbers
Louda Petr
2015-01-01
Full Text Available The work deals with the numerical simulation of 3D turbulent flow over backward facing step in a narrow channel. The mathematical model is based on the RANS equations with an explicit algebraic Reynolds stress model (EARSM. The numerical method uses implicit finite volume upwind discretization. While the eddy viscosity models fail in predicting complex 3D flows, the EARSM model is shown to provide results which agree well with experimental PIV data. The reference experimental data provide the 3D flow field. The simulations are compared with experiment for 3 values of Reynolds number.
Simulação 3D de movimento ortodôntico 3D simulation of orthodontic tooth movement
Norman Duque Penedo
2010-10-01
Full Text Available OBJETIVO: desenvolver e validar, através do Método dos Elementos Finitos (MEF, um modelo numérico tridimensional (3D de um incisivo central superior para simular o movimento dentário. MÉTODOS: esse modelo contempla a unidade dentária, o osso alveolar e o ligamento periodontal. Permite a simulação dos diferentes movimentos dentários e a determinação dos centros de rotação e de resistência. Limita o movimento ao espaço periodontal, registrando a direção, quantificando o deslocamento dentário e as tensões iniciais no ligamento periodontal. RESULTADOS: a análise dos deslocamentos dentários e das áreas que recebem tensões iniciais possibilita determinar os tipos de movimentos dentários. Com base nas forças ortodônticas, é possível quantificar a intensidade das tensões em cada região do dente, do ligamento periodontal ou do osso alveolar. Com base nas tensões axiais ao longo do ligamento periodontal e da tensão capilar, é possível predizer, teoricamente, as regiões em que deve ocorrer a remodelação óssea. CONCLUSÃO: o modelo foi validado pela determinação do módulo de elasticidade do ligamento periodontal de forma compatível com dados experimentais existentes na literatura. Os métodos utilizados na construção do modelo permitiram a criação de um modelo completo para uma arcada dentária, o qual possibilita realizar variadas simulações que envolvem a mecânica ortodôntica.OBJECTIVE: To develop and validate a three-dimensional (3D numerical model of a maxillary central incisor to simulate tooth movement using the Finite Element Method (FEM. METHODS: This model encompasses the tooth, alveolar bone and periodontal ligament. It allows the simulation of different tooth movements and the establishment of centers of rotation and resistance. It limits the movement into the periodontal space, recording the direction, quantifying tooth displacement and initial stress in the periodontal ligament. RESULTS: By
The Effects of 3D Computer Simulation on Biology Students' Achievement and Memory Retention
Elangovan, Tavasuria; Ismail, Zurida
2014-01-01
A quasi experimental study was conducted for six weeks to determine the effectiveness of two different 3D computer simulation based teaching methods, that is, realistic simulation and non-realistic simulation on Form Four Biology students' achievement and memory retention in Perak, Malaysia. A sample of 136 Form Four Biology students in Perak,…
3D multiple-point statistics simulation using 2D training images
Comunian, A.; Renard, P.; Straubhaar, J.
2012-03-01
One of the main issues in the application of multiple-point statistics (MPS) to the simulation of three-dimensional (3D) blocks is the lack of a suitable 3D training image. In this work, we compare three methods of overcoming this issue using information coming from bidimensional (2D) training images. One approach is based on the aggregation of probabilities. The other approaches are novel. One relies on merging the lists obtained using the impala algorithm from diverse 2D training images, creating a list of compatible data events that is then used for the MPS simulation. The other (s2Dcd) is based on sequential simulations of 2D slices constrained by the conditioning data computed at the previous simulation steps. These three methods are tested on the reproduction of two 3D images that are used as references, and on a real case study where two training images of sedimentary structures are considered. The tests show that it is possible to obtain 3D MPS simulations with at least two 2D training images. The simulations obtained, in particular those obtained with the s2Dcd method, are close to the references, according to a number of comparison criteria. The CPU time required to simulate with the method s2Dcd is from two to four orders of magnitude smaller than the one required by a MPS simulation performed using a 3D training image, while the results obtained are comparable. This computational efficiency and the possibility of using MPS for 3D simulation without the need for a 3D training image facilitates the inclusion of MPS in Monte Carlo, uncertainty evaluation, and stochastic inverse problems frameworks.
Fire simulation for a 3D character with particles and motion capture data in Blender
Hoikkala, Ville
2016-01-01
The object of this thesis was to study particle based simulations in 3D and how they can be applied to motion capture data. The theoretical part examines the history of 3D and computer graphics concisely and finally particles and simulations. The practical part consists of the case-work involving a fire emitting particle simulation. The study examines two methods of creating a fire simulation in Blender and how they influence the outlook of the particles. It was found that the fire si...
NVision: A 3D Visualization Environment for N-Body Simulations
Markiel, J. A.
2000-05-01
NVision: A 3D Visualization Environment for N-Body Simulations We are developing a set of packages for 3D visualization and analysis of our numerical N-body simulations. These tools are intended to be generalizable to a wide range of related problems including cosmological, planetary dynamics, and molecular dynamics simulations. The applications and source code will be fully available to the community. To prototype this project we have adopted the Java platform with the newly released Java3D extension to take advantage of its portability, object-oriented environment, and availability of extensive documentation and class libraries. We will describe the goals and design principles of the project and demo the currently implemented features, including visualization of cosmological simulations and the simulated collision of two rubble-pile asteroids. This research is supported by NSF grants AST99-73209 and AST99-79891.
Completion of PCFLOW3D Model for Simulation of Flow and Dispersion of Pollutants
Kovšca, Jasna
2007-01-01
An upgrade of the three-dimensional baroclinic mathematical model PCFLOW3D with a new turbulence model Smagorinsky-vertical is presented. Several test cases were made to compare this new turbulence model with other turbulence models already built in the PCFLOW3D model. Additional verifications of the test results were performed using the commercial software CORMIX of which main purpose is to simulate the near field areas of pollution inflows. CORMIX is restricted to steady flow...
3D-Simulation und Planung von Anlagen der Hütten- und Walzwerkstechnik
Oppermann, Ingo
2009-01-01
In der Präsentation werden typische Engineeringaufgaben präsentiert, die mit modernen IT-Werkzeugen erledigt werden. Es wird auf die Einführung und die Durchgängigkeit eines 3D-CAD-Systems eingegangen und gezeigt, wie mit diesem System Simulations- und Prozesskettenthemen in der Praxis bei der SMS Siemag AG behandelt werden. Ebenfalls anhand von Beispielen wird die Thematik der großen Baugruppen und der Anlagenplanung im 3D-Engineering dargestellt.
Efficient use of 3d environment models for mobile robot simulation and localization
Corominas Murtra, Andreu; Trulls, Eduard; Mirats-Tur, Josep M.; Sanfeliu, Alberto
2010-01-01
This paper provides a detailed description of a set of algorithms to efficiently manipulate 3D geometric models to compute physical constraints and range observation models, data that is usually required in real-time mobile robotics or simulation. Our approach uses a standard file format to describe the environment and processes the model using the openGL library, a widely-used programming interface for 3D scene manipulation. The paper also presents results on a test model for benchmarking, a...
Web-Based 3D and Haptic Interactive Environments for e-Learning, Simulation, and Training
Hamza-Lup, Felix G.; Sopin, Ivan
Knowledge creation occurs in the process of social interaction. As our service-based society is evolving into a knowledge-based society, there is an acute need for more effective collaboration and knowledge-sharing systems to be used by geographically scattered people. We present the use of 3D components and standards, such as Web3D, in combination with the haptic paradigm, for e-Learning and simulation.
Simulations of Coulomb systems with slab geometry using an efficient 3D Ewald summation method
dos Santos, Alexandre P.; Girotto, Matheus; Levin, Yan
2016-04-01
We present a new approach to efficiently simulate electrolytes confined between infinite charged walls using a 3d Ewald summation method. The optimal performance is achieved by separating the electrostatic potential produced by the charged walls from the electrostatic potential of electrolyte. The electric field produced by the 3d periodic images of the walls is constant inside the simulation cell, with the field produced by the transverse images of the charged plates canceling out. The non-neutral confined electrolyte in an external potential can be simulated using 3d Ewald summation with a suitable renormalization of the electrostatic energy, to remove a divergence, and a correction that accounts for the conditional convergence of the resulting lattice sum. The new algorithm is at least an order of magnitude more rapid than the usual simulation methods for the slab geometry and can be further sped up by adopting a particle-particle particle-mesh approach.
3D Simulation of External Flooding Events for the RISMC Pathway
Incorporating 3D simulations as part of the Risk-Informed Safety Margins Characterization (RISMIC) Toolkit allows analysts to obtain a more complete picture of complex system behavior for events including external plant hazards. External events such as flooding have become more important recently – however these can be analyzed with existing and validated simulated physics toolkits. In this report, we describe these approaches specific to flooding-based analysis using an approach called Smoothed Particle Hydrodynamics. The theory, validation, and example applications of the 3D flooding simulation are described. Integrating these 3D simulation methods into computational risk analysis provides a spatial/visual aspect to the design, improves the realism of results, and can prove visual understanding to validate the analysis of flooding.
3D Simulation of External Flooding Events for the RISMC Pathway
Prescott, Steven [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sampath, Ramprasad [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lin, Linyu [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-09-01
Incorporating 3D simulations as part of the Risk-Informed Safety Margins Characterization (RISMIC) Toolkit allows analysts to obtain a more complete picture of complex system behavior for events including external plant hazards. External events such as flooding have become more important recently – however these can be analyzed with existing and validated simulated physics toolkits. In this report, we describe these approaches specific to flooding-based analysis using an approach called Smoothed Particle Hydrodynamics. The theory, validation, and example applications of the 3D flooding simulation are described. Integrating these 3D simulation methods into computational risk analysis provides a spatial/visual aspect to the design, improves the realism of results, and can prove visual understanding to validate the analysis of flooding.
A global simulation of ICRF heating in a 3D magnetic configuration
A global simulation code for the ICRF heating analysis in a three-dimensional (3D) magnetic configuration is developed combining two global simulation codes; a drift kinetic equation solver, GNET, and a wave field solver, TASK/WM. Both codes take into account 3D geometry using the numerically obtained 3D MHD equilibrium. The developed simulation code is applied to the LHD configuration as an example. Characteristics of energetic ion distributions in the phase space are clarified in LHD. The simulation results are also compared with experimental results by evaluating the count number of the neutral particle analyzer using the obtained energetic ion distribution, and a relatively good agreement is obtained. (author)
Steven Prescott; Ramprasad Sampath; Curtis Smith; Tony Koonce
2014-09-01
Computers have been used for 3D modeling and simulation, but only recently have computational resources been able to give realistic results in a reasonable time frame for large complex models. This report addressed the methods, techniques, and resources used to develop a prototype for using 3D modeling and simulation engine to improve risk analysis and evaluate reactor structures and components for a given scenario. The simulations done for this evaluation were focused on external events, specifically tsunami floods, for a hypothetical nuclear power facility on a coastline.
Application of 3-D numerical simulation software SRIFCAST to produce ductile iron castings
无
2005-01-01
Based on a method using numerical simulation equations and their solution schemes for liquid metal flows and heat transfer during mold filling and the solidification process of casting, 3-D numerical simulation software SRIFCAST was created. This includes enmeshment of casting; velocity and temperature fields calculation; displaying iso-temperature lines;velocity vectors and 3-D temperature fields on a Windows 9x operating system. SRIFCAST was applied to produce sound castings of automobile and diesel engines, and also to connect with microstructure simulation for ductile iron castings.
The M3D-C1 Approach to Simulating 3D 2-fluid Magnetohydrodynamics in Magnetic Fusion Experiments
A new approach for solving the 3D MHD equations in a strongly magnetized toroidal plasma is presented which uses high-order 2D finite elements with C1 continuity. The vector fields use a physics-based decomposition. An efficient implicit time advance separates the velocity and field advance. ITAPS (SCOREC) adaptivity software and TOPS solvers are used
Calculation of residual stresses by means of a 3D numerical weld simulation
Nicak, Tomas; Huemmer, Matthias [AREVA NP GmbH, Postfach 1109 (Germany)
2008-07-01
The numerical weld simulation has developed very fast in recent years. The problem complexity has increased from simple 2D models to full 3D models, which can describe the entire welding process more realistically. As recent research projects indicate, a quantitative assessment of the residual stresses by means of a 3D analysis is possible. The structure integrity can be assessed based on the weld simulation results superimposed with the operating load. Moreover, to support the qualification of welded components parametric studies for optimization of the residual stress distribution in the weld region can be performed. In this paper a full 3D numerical weld simulation for a man-hole drainage nozzle in a steam generator will be presented. The residual stresses are calculated by means of an uncoupled transient thermal and mechanical FE analysis. The paper will present a robust procedure allowing reasonable predictions of the residual stresses for complex structures in industrial practice. (authors)
Grinberg, L; Cheever, E; Anor, T; Madsen, J R; Karniadakis, G E
2011-01-01
We compare results from numerical simulations of pulsatile blood flow in two patient-specific intracranial arterial networks using one-dimensional (1D) and three-dimensional (3D) models. Specifically, we focus on the pressure and flowrate distribution at different segments of the network computed by the two models. Results obtained with 1D and 3D models with rigid walls show good agreement in massflow distribution at tens of arterial junctions and also in pressure drop along the arteries. The 3D simulations with the rigid walls predict higher amplitude of the flowrate and pressure temporal oscillations than the 1D simulations with compliant walls at various segments even for small time-variations in the arterial cross-sectional areas. Sensitivity of the flow and pressure with respect to variation in the elasticity parameters is investigated with the 1D model. PMID:20661645
Simulating binocular vision for no-reference 3D visual quality measurement.
Zhou, Wu-Jie; Yu, Lu; Wu, Ming-Wei
2015-09-01
Perceptual quality measurement of three-dimensional (3D) visual signals has become a fundamental challenge in 3D imaging fields. This paper proposes a novel no-reference (NR) 3D visual quality measurement (VQM) metric that uses simulations of the primary visual cortex (V1) of binocular vision. As the major technical contribution of this study, perceptual properties of simple and complex cells are considered for NR 3D-VQM. More specifically, the metric simulates the receptive fields of simple cells (one class of V1 neurons) using Gaussian derivative functions, and the receptive fields of complex cells (the other class of V1 neurons) using disparity energy responses and binocular rivalry responses. Subsequently, various quality-aware features are extracted from the primary visual cortex; these will change in the presence of distortions. Finally, those features are mapped to the subjective quality score of the distorted 3D visual signal by using support vector regression (SVR). Experiments on two publicly available 3D databases confirm the effectiveness of our proposed metric, compared to the relevant full-reference (FR) and NR metrics. PMID:26368467
Madura, Thomas; Gull, Theodore R.; Clementel, Nicola; Paardekooper, Jan-Pieter; Kruip, Chael; Corcoran, Michael F.; Hamaguchi, Kenji; Teodoro, Mairan
2015-01-01
We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (>120 MSun), highly eccentric (e ~ 0.9) binary Eta Carinae. Using a consumer-grade 3D printer (Makerbot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics simulations of Eta Carinae's inner (r ~110 AU) wind-wind collision interface at multiple orbital phases. These 3D prints reveal important, previously unknown 'finger-like' structures at orbital phases shortly after periastron (φ ~1.045) that protrude radially outward from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. Rayleigh-Taylor) that arise at the interface between the radiatively-cooled layer of dense post-shock primary-star wind and the hot, adiabatic post-shock companion-star wind. The success of our work and easy identification of previously unknown physical features highlight the important role 3D printing can play in the visualization and understanding of complex 3D time-dependent numerical simulations of astrophysical phenomena.
Simulation of Missing Pellet Surface thermal behavior with 3D dynamic gap element
Most of the fuel performance codes that are able to simulate a multidimensional analysis are used to calculate the radial temperature distribution and perform a multidimensional mechanical analysis based on a one-dimensional (1D) temperature result. The FRAPCON-FRAPTRAN code system incorporates a 1D thermal module and two-dimensional (2D) mechanical module when FEM option is activated. In this method, the multidimensional gap conductance model is not required because one-dimensional thermal analysis is carried out. On the other hand, a gap conductance model for a multi-dimension should be developed in the code to perform a multidimensional thermal analysis. ALCYONE developed by CEA introduces an equivalent heat convection coefficient that represents the multidimensional gap conductance. However, the code does not employ dynamic gap conductance which is a function of gap thickness and gap characteristics in direct. The BISON code, which has been developed by INL (Idaho National Laboratory), employed a thermo-mechanical contact method that is specifically designed for tightly-coupled implicit solutions that employ Jacobian-free solution methods. Owing to tightly-coupled implicit solutions, the BISON code solves gap conductance and gap thickness simultaneously with given boundary conditions. In this paper, 3D dynamic gap element has been proposed to resolve convergence issue and nonlinear characteristic of multidimensional gap conductance. To evaluate 3D dynamic gap element module, 3D thermomechanical module using FORTRAN77 has been implemented incorporating 3D dynamic gap element. To demonstrate effect of 3D dynamic gap element, thermal behavior of missing pellet surface (MPS) has been simulated by the developed module. LWR fuel performance codes should incorporate thermo-mechanical loop to solve gap conductance problem, iteratively. However, gap conductance in multidimensional model is difficult issue owing to its nonlinearity and convergence characteristics. In
Study of 3-D Numerical Simulation for Gas Transfer in the Goaf of the Coal Mining
WU Zheng-yan; JIANG Shu-guang; HE Xin-jian; WANG Lan-yun; LIN Bai-quan
2007-01-01
In order to simulate field distribution rules, mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established, based on theories of permeability and dynamic dispersion through porous media. A gas dispersion equation in a 3-D field is calculated by use of numerical method on a weighted upstream multi-element balance. Based on data of an example with a U type ventilation mode, surface charts of air pressure distribution and gas concentration are drawn by Graphtool software. Finally, a comparison between actually measured results in the model test and the numerical simulation results is made to proves the numerical implementation feasible.
3-D NUMERICAL SIMULATION OF FLOW THROUGH AN ORIFICE SPILL-WAY TUNNEL
无
2002-01-01
A Large Eddy Simulation (LES) approachbased on the weakly compressible hydrodynamic equation with a single-plase fluid model for the cavitation flow has been de-veloped and employed in simulating 3-D unsteady viscous flowthrough an orifice type spillwy tunnel. The finite volume ap-proach in space and the predictor-corrector method in timehave been used to the numerical discretization, and the "Lawof wall" is applied at the solid boundary. The velocity, pres-sure fields and the cavitation phenomenon are obtained, thecomputational results show that 3-D LES approach can givemore realistic flow field prediction of the orifice type spillwaytunnel.
CONEX and CORSIKA: a new 3D hybrid model for air shower simulation
The hybrid air shower simulation code CONEX has been implemented as an option in the air shower Monte-Carlo model CORSIKA. In CONEX, Monte-Carlo simulation of high energy interactions is combined with a fast numerical solution of cascade equations. Low energy secondary particles can then be tracked within CORSIKA to obtain the lateral extension of the air shower. This allows the fast and realistic simulation of 3D showers at ultra-high energies.
Schulte, Claudia; Coors, Volker; Eicker, Ursula [Hochschule fuer Technik (HFT), Stuttgart (Germany)
2012-07-01
The biggest potential for heat consumption reduction and CO2 emission reduction in Germany is in older buildings. By applying innovative modernization concepts, primary energy consumption could be reduced by 80 percent. Planning of modernisation and energy concepts requires data on the current status. HFT Stuttgart developed a promising method for assessing heat consumption according to DIN 18599 of urban districts on the basis of 3D models of buildings (CityGML). The method is presented and explained here.
Ground motion simulations in Marmara (Turkey) region from 3D finite difference method
Aochi, Hideo; Ulrich, Thomas; Douglas, John
2016-04-01
In the framework of the European project MARSite (2012-2016), one of the main contributions from our research team was to provide ground-motion simulations for the Marmara region from various earthquake source scenarios. We adopted a 3D finite difference code, taking into account the 3D structure around the Sea of Marmara (including the bathymetry) and the sea layer. We simulated two moderate earthquakes (about Mw4.5) and found that the 3D structure improves significantly the waveforms compared to the 1D layer model. Simulations were carried out for different earthquakes (moderate point sources and large finite sources) in order to provide shake maps (Aochi and Ulrich, BSSA, 2015), to study the variability of ground-motion parameters (Douglas & Aochi, BSSA, 2016) as well as to provide synthetic seismograms for the blind inversion tests (Diao et al., GJI, 2016). The results are also planned to be integrated in broadband ground-motion simulations, tsunamis generation and simulations of triggered landslides (in progress by different partners). The simulations are freely shared among the partners via the internet and the visualization of the results is diffused on the project's homepage. All these simulations should be seen as a reference for this region, as they are based on the latest knowledge that obtained during the MARSite project, although their refinement and validation of the model parameters and the simulations are a continuing research task relying on continuing observations. The numerical code used, the models and the simulations are available on demand.
2D-3D hybrid stabilized finite element method for tsunami runup simulations
Takase, S.; Moriguchi, S.; Terada, K.; Kato, J.; Kyoya, T.; Kashiyama, K.; Kotani, T.
2016-09-01
This paper presents a two-dimensional (2D)-three-dimensional (3D) hybrid stabilized finite element method that enables us to predict a propagation process of tsunami generated in a hypocentral region, which ranges from offshore propagation to runup to urban areas, with high accuracy and relatively low computational costs. To be more specific, the 2D shallow water equation is employed to simulate the propagation of offshore waves, while the 3D Navier-Stokes equation is employed for the runup in urban areas. The stabilized finite element method is utilized for numerical simulations for both of the 2D and 3D domains that are independently discretized with unstructured meshes. The multi-point constraint and transmission methods are applied to satisfy the continuity of flow velocities and pressures at the interface between the resulting 2D and 3D meshes, since neither their spatial dimensions nor node arrangements are consistent. Numerical examples are presented to demonstrate the performance of the proposed hybrid method to simulate tsunami behavior, including offshore propagation and runup to urban areas, with substantially lower computation costs in comparison with full 3D computations.
A Jones matrix formalism for simulating 3D Polarised Light Imaging of brain tissue
Menzel, Miriam; De Raedt, Hans; Reckfort, Julia; Amunts, Katrin; Axer, Markus
2015-01-01
The neuroimaging technique 3D Polarised Light Imaging (3D-PLI) provides a high-resolution reconstruction of nerve fibres in human post-mortem brains. The orientations of the fibres are derived from birefringence measurements of histological brain sections assuming that the nerve fibres - consisting of an axon and a surrounding myelin sheath - are uniaxial birefringent and that the measured optic axis is oriented in direction of the nerve fibres (macroscopic model). Although experimental studies support this assumption, the molecular structure of the myelin sheath suggests that the birefringence of a nerve fibre can be described more precisely by multiple optic axes oriented radially around the fibre axis (microscopic model). In this paper, we compare the use of the macroscopic and the microscopic model for simulating 3D-PLI by means of the Jones matrix formalism. The simulations show that the macroscopic model ensures a reliable estimation of the fibre orientations as long as the polarimeter does not resolve ...
3D numerical simulation analysis of passive drag near free surface in swimming
Zhan, Jie-min; Li, Tian-zeng; Chen, Xue-bin; Li, Yok-sheung; Wai, Wing-hong Onyx
2015-04-01
The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k- ɛ turbulence closure. The volume of fluid (VOF) method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design (CAID) software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer's arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.
GRASIL-3D: an Implemention of Dust Effects in the SEDs of Simulated Galaxies
Domínguez-Tenreiro, R; Granato, G L; Schurer, A; Alpresa, P; Silva, L; Brook, C B; Serna, A
2013-01-01
We introduce a new model for the spectral energy distribution of galaxies, GRASIL-3D, which includes a careful modelling of the dust component of the interstellar medium. GRASIL-3D is an entirely new model based on the formalism of an existing and widely applied spectrophotometric model, GRASIL, but specifically designed to be interfaced with galaxies with any arbitrarily given geometry, such as galaxies calculated by theoretical hydrodynamical galaxy formation codes. GRASIL-3D is designed to separately treat radiative transfer in molecular clouds and in the diffuse cirrus component. The code has a general applicability to the outputs of simulated galaxies, either from Lagrangian or Eulerian hydrodynamic codes. As an application, the new model has been interfaced to the P-DEVA and GASOLINE smoothed-particle hydrodynamic codes, and has been used to calculate the spectral energy distribution for a variety of simulated galaxies from UV to sub-millimeter wavelengths, whose comparison with observational data gives...
Kempka, Thomas; Nakaten, Benjamin; De Lucia, Marco; Nakaten, Natalie; Otto, Christopher; Pohl, Maik; Tillner, Elena; Kühn, Michael
2016-04-01
Utilization of the geological subsurface for production and storage of hydrocarbons, chemical energy and heat as well as for waste disposal requires the quantification and mitigation of environmental impacts as well as the improvement of georesources utilization in terms of efficiency and sustainability. The development of tools for coupled process simulations is essential to tackle these challenges, since reliable assessments are only feasible by integrative numerical computations. Coupled processes at reservoir to regional scale determine the behaviour of reservoirs, faults and caprocks, generally demanding for complex 3D geological models to be considered besides available monitoring and experimenting data in coupled numerical simulations. We have been developing a flexible numerical simulation framework that provides efficient workflows for integrating the required data and software packages to carry out coupled process simulations considering, e.g., multiphase fluid flow, geomechanics, geochemistry and heat. Simulation results are stored in structured data formats to allow for an integrated 3D visualization and result interpretation as well as data archiving and its provision to collaborators. The main benefits in using the flexible simulation framework are the integration of data geological and grid data from any third party software package as well as data export to generic 3D visualization tools and archiving formats. The coupling of the required process simulators in time and space is feasible, while different spatial dimensions in the coupled simulations can be integrated, e.g., 0D batch with 3D dynamic simulations. User interaction is established via high-level programming languages, while computational efficiency is achieved by using low-level programming languages. We present three case studies on the assessment of geological subsurface utilization based on different process coupling approaches and numerical simulations.
Simulation System Design of 3-D Panorama of Ship Motions in Wave
LIU Ya-dong; LI Ji-de; LI Zhen
2002-01-01
In this paper a 3-D panoramic simulation system of a ship is described which is developed with the MAXSCRIPT language and VC++ as programming tools on the platform of 3Dsmax. The strip theory method is applied to the motion prediction of the mono-hull. The time history solutions of heave and pitch are obtained in the condition of head sea to provide the primary data on panoramic simulation. The simulation system has following functions: 1)digital simulation;2) panoramic simulation; 3) environmental set-up; 4) render preview and output.
Development of 3D dynamic gap element for simulation of asymmetric fuel behavior
The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding the fuel performance, including cladding stress and behavior under irradiated conditions. To establish a heat transfer model through a gap in the fuel performance code, the gap conductance based on the Ross and Stoute model was employed in most previous works. In this model, the gap conductance that determines the temperature gradient within the gap is a function of gap thickness, which is dependent on mechanical behavior. Recently, many researchers have been developing fuel performance codes based on the finite element method (FE) to calculate the temperature, stress, and strain in 2D or 3D. The gap conductance model for FE can be a challenging issue in terms of convergence and nonlinearity because the elements that are positioned in a gap have a different gap conductance, and the boundary conditions of the gap vary at each iteration step. In this paper, the specified 3D dynamic gap element has been proposed and implemented to simulate asymmetric thermo-mechanical fuel behavior. A thermo-mechanical 3D finite element module incorporating a gap element has been implemented using FORTRAN77. To evaluate the proposed 3D gap element, the missing pellet surface (MPS), which results in an asymmetric heat transfer in the pellet and cladding, was simulated. As a result, the maximum temperature of a pellet for the MPS problem calculated with the specified 3D gap element is much higher than the temperature calculated with a uniform gap conductance model that a multidimensional fuel performance code employs. The results demonstrate that a 3D simulation is essential to evaluate the temperature and stress of the pellet and cladding for an asymmetric geometry simulation. (author)
Renal Tumor Cryoablation Planning. The Efficiency of Simulation on Reconstructed 3D CT Scan
Ciprian Valerian LUCAN
2010-12-01
Full Text Available Introduction & Objective: Nephron-sparing surgical techniques risks are related to tumor relationships with adjacent anatomic structures. Complexity of the renal anatomy drives the interest to develop tools for 3D reconstruction and surgery simulation. The aim of the article was to assess the simulation on reconstructed 3D CT scan used for planning the cryoablation. Material & Method: A prospective randomized study was performed between Jan. 2007 and July 2009 on 27 patients who underwent retroperitoneoscopic T1a renal tumors cryoablation (RC. All patients were assessed preoperatively by CT scan, also used for 3D volume rendering. In the Gr.A, the patients underwent surgery planning by simulation on 3D CT scan. In the Gr.B., patients underwent standard RC. The two groups were compared in terms of surgical time, bleeding, postoperative drainage, analgesics requirement, hospital stay, time to socio-professional reintegration. Results: Fourteen patients underwent preoperative cryoablation planning (Gr.A and 13 patients underwent standard CR (Gr.B. All parameters analyzed were shorter in the Gr.A. On multivariate logistic regression, only shortens of the surgical time (138.79±5.51 min. in Gr.A. vs. 140.92±5.54 min in Gr.B. and bleeding (164.29±60.22 mL in Gr.A. vs. 215.38±100.80 mL in Gr.B. achieved statistical significance (p<0.05. The number of cryoneedles assessed by simulation had a 92.52% accuracy when compared with those effectively used. Conclusions: Simulation of the cryoablation using reconstructed 3D CT scan improves the surgical results. The application used for simulation was able to accurately assess the number of cryoneedles required for tumor ablation, their direction and approach.
An Object-Oriented Simulator for 3D Digital Breast Tomosynthesis Imaging System
Saeed Seyyedi
2013-01-01
Full Text Available Digital breast tomosynthesis (DBT is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART and total variation regularized reconstruction techniques (ART+TV are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM values.
WANG Xin-yun; GUO Zhi-feng; QINWen-hans; SUN Guo-qing
2011-01-01
It is difficulties for the computer simulation method to study radiation regime at large-scale.Simplified coniferous model was investigated in the present study.It makes the computer simulation methods such as L-systems and radiosity-graphics combined method (RGM) more powerful in remote sensing of heterogeneous coniferous forests over a large-scale region.L-systems is applied to render 3-D coniferous forest scenarios,and RGM model was used to calculate BRF (bidirectional reflectance factor) in visible and near-infrared regions.Results in this study show that in most cases both agreed well Meanwhile at a tree and forest level,the results are also good.
Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.
2014-01-01
Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in Eta Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in Eta Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form. We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for Eta Car.
3D CFD Simulations of MOCVD Synthesis System of Titanium Dioxide Nanoparticles
Siti Hajar Othman; Suraya Abdul Rashid; Tinia Idaty Mohd Ghazi; Norhafizah Abdullah
2013-01-01
This paper presents the 3-dimensional (3D) computational fluid dynamics (CFD) simulation study of metal organic chemical vapor deposition (MOCVD) producing photocatalytic titanium dioxide (TiO2) nanoparticles. It aims to provide better understanding of the MOCVD synthesis system especially of deposition process of TiO2 nanoparticles as well as fluid dynamics inside the reactor. The simulated model predicts temperature, velocity, gas streamline, mass fraction of reactants and products, kinetic...
Finite Volume Particle Method for 3-D Elasto-Plastic Solid Simulation
Jahanbakhsh, Ebrahim; Vessaz, Christian; Avellan, François
2014-01-01
Finite Volume Particle Method was successfully used to predict fluid flow behavior for 2-D simulations. In this paper, we present a FVPM which is applicable for 3-D solid mechanics simulations. This method features rectangular top-hat kernels for computing the interaction vectors exactly and efficiently. We employed this method to solve the elasto-plastic constitutive equations. To validate the model, we study the impact of rigid spherical particle to the solid surface with different velociti...
Neutron-induced complex reaction analysis with 3D nuclear track simulation
Complex (multiple) etched tracks are analysed through digitised images and 3D simulation by a purpose-built algorithm. From a binary track image an unfolding procedure is followed to generate a 3D track model, from which several track parameters are estimated. The method presented here allows the deposited energy, that originated from particle fragmentation or carbon spallation by means of induced tracks in commercially available PADC detectors, to be estimated. Results of evaluated nuclear tracks related to 12C (n,3αn') reaction are presented here. The detectors were exposed on the ISS in 2001
3D FEM Simulation of Rolling Load Working on Piercer Plug in Mannesmann Piercing Process
Yoshida, Motohisa
2010-06-01
This paper presents 3D FEM simulation of piercer plug in Mannesmann piercing process. Target is establishment of a virtual piercing experiment tool to assistant piercer plug development. FEM simulation analysis has been applied to Mannesmann piercing process previously. Aspect of those studies is how to simulate material flow in piercing process, especially focused on how to describe ductile fracture which is known as Mannesmann effect. Thus far, simulation of rolling tools has not been focused. Present piercer plugs, made of special alloys, are damaged severely and quickly in case of piercing higher Cr contented alloys in seamless steel tube production process. Therefore, development of FEM simulation on rolling tools has been demanded in production side. 3D FEM analysis of piercer plug is performed with ALE (Arbitrary Lagrangian—Eulerian) method by using ABAQUS/Explicit 6.9. Simulations are thermo-mechanical, elasto-plastic coupled, and dynamic calculation. Piercer plug and the billet are modeled by solid elements to analyze various factors on stress, strain and temperature. Ductile fracture is not considered in the simulations. Simulation results are correlated sufficiently to experimental results on damage of piercer plugs. Verifying absolute value of simulated factors is hard since there are few empirical methods to measure them. As a conclusion, studied simulations are sufficient as a virtual piercing experiment tool to develop higher performance piercer plugs.
Simulations of 3D-Si sensors for the innermost layer of the ATLAS pixel upgrade
Baselga, Marta; Quirion, David
2016-01-01
The LHC is expected to reach luminosities up to 3000fb-1 and the innermost layer of the ATLAS upgrade plans to cope with higher occupancy and to decrease the pixel size. 3D-Si sensors are a good candidate for the innermost layer of the ATLAS pixel upgrade since they exhibit good performance under high fluences and the new designs will have smaller pixel size to fulfill the electronics expectations. This paper reports TCAD simulations of the 3D-Si sensors designed at IMB-CNM with non passing-through columns that are being fabricated for the next innermost layer of the ATLAS pixel upgrade, shows the charge collection response before and after irradiation, and the response of 3D-Si sensors located at large $\\eta$ angles.
As part of its activity, EDF R and D is developing a new nuclear core simulation code named COCAGNE. This code relies on DIABOLO, a Simplified PN (SPN) method to compute the neutron flux inside the core for eigenvalue calculations. In order to assess the accuracy of SPN calculations, we have developed DOMINO, a new 3D Cartesian SN solver. The parallel implementation of DOMINO is very efficient and allows to complete an eigenvalue calculation involving around 300 x 109 degrees of freedom within a few hours on a single shared-memory supercomputing node. This computation corresponds to a 26-group S8 3D PWR core model used to assess the SPN accuracy. At the pin level, the maximal error for the SP5 DIABOLO fission production rate is lower than 0.2% compared to the S8 DOMINO reference for this 3D PWR core model. (authors)
Courau, T.; Moustafa, S.; Plagne, L.; Poncot, A. [EDF R and D, 1, Av du General de Gaulle, F92141 Clamart cedex (France)
2013-07-01
As part of its activity, EDF R and D is developing a new nuclear core simulation code named COCAGNE. This code relies on DIABOLO, a Simplified PN (SPN) method to compute the neutron flux inside the core for eigenvalue calculations. In order to assess the accuracy of SPN calculations, we have developed DOMINO, a new 3D Cartesian SN solver. The parallel implementation of DOMINO is very efficient and allows to complete an eigenvalue calculation involving around 300 x 10{sup 9} degrees of freedom within a few hours on a single shared-memory supercomputing node. This computation corresponds to a 26-group S{sub 8} 3D PWR core model used to assess the SPN accuracy. At the pin level, the maximal error for the SP{sub 5} DIABOLO fission production rate is lower than 0.2% compared to the S{sub 8} DOMINO reference for this 3D PWR core model. (authors)
3D dynamic simulation of crack propagation in extracorporeal shock wave lithotripsy
Some experimental observations of Shock Wave Lithotripsy(SWL), which include 3D dynamic crack propagation, are simulated with the aim of reproducing fragmentation of kidney stones with SWL. Extracorporeal shock wave lithotripsy (ESWL) is the fragmentation of kidney stones by focusing an ultrasonic pressure pulse onto the stones. 3D models with fine discretization are used to accurately capture the high amplitude shear shock waves. For solving the resulting large scale dynamic crack propagation problem, PDS-FEM is used; it provides numerically efficient failure treatments. With a distributed memory parallel code of PDS-FEM, experimentally observed 3D photoelastic images of transient stress waves and crack patterns in cylindrical samples are successfully reproduced. The numerical crack patterns are in good agreement with the experimental ones, quantitatively. The results shows that the high amplitude shear waves induced in solid, by the lithotriptor generated shock wave, play a dominant role in stone fragmentation.
Jung, Jaewoon; Kobayashi, Chigusa; Imamura, Toshiyuki; Sugita, Yuji
2016-03-01
Three-dimensional Fast Fourier Transform (3D FFT) plays an important role in a wide variety of computer simulations and data analyses, including molecular dynamics (MD) simulations. In this study, we develop hybrid (MPI+OpenMP) parallelization schemes of 3D FFT based on two new volumetric decompositions, mainly for the particle mesh Ewald (PME) calculation in MD simulations. In one scheme, (1d_Alltoall), five all-to-all communications in one dimension are carried out, and in the other, (2d_Alltoall), one two-dimensional all-to-all communication is combined with two all-to-all communications in one dimension. 2d_Alltoall is similar to the conventional volumetric decomposition scheme. We performed benchmark tests of 3D FFT for the systems with different grid sizes using a large number of processors on the K computer in RIKEN AICS. The two schemes show comparable performances, and are better than existing 3D FFTs. The performances of 1d_Alltoall and 2d_Alltoall depend on the supercomputer network system and number of processors in each dimension. There is enough leeway for users to optimize performance for their conditions. In the PME method, short-range real-space interactions as well as long-range reciprocal-space interactions are calculated. Our volumetric decomposition schemes are particularly useful when used in conjunction with the recently developed midpoint cell method for short-range interactions, due to the same decompositions of real and reciprocal spaces. The 1d_Alltoall scheme of 3D FFT takes 4.7 ms to simulate one MD cycle for a virus system containing more than 1 million atoms using 32,768 cores on the K computer.
Simulation of bootstrap current in 2D and 3D ideal magnetic fields in tokamaks
Raghunathan, M.; Graves, J. P.; Cooper, W. A.; Pedro, M.; Sauter, O.
2016-09-01
We aim to simulate the bootstrap current for a MAST-like spherical tokamak using two approaches for magnetic equilibria including externally caused 3D effects such as resonant magnetic perturbations (RMPs), the effect of toroidal ripple, and intrinsic 3D effects such as non-resonant internal kink modes. The first approach relies on known neoclassical coefficients in ideal MHD equilibria, using the Sauter (Sauter et al 1999 Phys. Plasmas 6 2834) expression valid for all collisionalities in axisymmetry, and the second approach being the quasi-analytic Shaing–Callen (Shaing and Callen 1983 Phys. Fluids 26 3315) model in the collisionless regime for 3D. Using the ideal free-boundary magnetohydrodynamic code VMEC, we compute the flux-surface averaged bootstrap current density, with the Sauter and Shaing–Callen expressions for 2D and 3D ideal MHD equilibria including an edge pressure barrier with the application of resonant magnetic perturbations, and equilibria possessing a saturated non-resonant 1/1 internal kink mode with a weak internal pressure barrier. We compare the applicability of the self-consistent iterative model on the 3D applications and discuss the limitations and advantages of each bootstrap current model for each type of equilibrium.
Twisting Rolls. Heuristic Model and 3D Numerical Simulation of Vortex Patterns
Bouali, S
2003-01-01
We connect an appropriate feedback loop to a model of 2D vertical eddy of airflow which unfolds a wide range of vorticity behavior. Computational fluid dynamics of the twisted roll display a class of long lifespan 3D vortices. On the one hand, the infinitely stable columnar vortex simulated describes waterspouts and tornadoes with extended lifetime. On the other hand, a light modification of the retroaction exhibits strong similarities to tropical cyclones. Moreover, we investigate the outcome of the twisting process vertically shifted. This modelisation leads to the simulation of simultaneous vortices associated to this other class of 3D vortices with short lifespan. Our heuristic dynamical systems lay the foundations of a comprehensive modelisation of vortices since it joins numerical simulations and theory.
Numerical Simulation of Injection Molding Cooling Process Based on 3D Surface Model
CUIShu-biao; ZHOUHua-min; LIDe-qun
2004-01-01
The design of the coohng system of injection molds directly affects both productivity and the quality of the final part. Using the cooling process CAE system to instruct the mold design, the efficiency and quality of design can be improved greatly. At the same time, it is helpful to confirm the cooling system structure and optimize the process conditions. In this paper, the 3D surface model of mold cavity is used to replace the middle-plane model in the simulation by Boundary Element Method, which break the bottleneck of the application of the injection molding simulation softwares base on the middle-plane model. With the improvements of this paper, a practical and commercial simulation software of injection molding cooling process named as HsCAE3D6.0 is developed.
Fast error simulation of optical 3D measurements at translucent objects
Lutzke, P.; Kühmstedt, P.; Notni, G.
2012-09-01
The scan results of optical 3D measurements at translucent objects deviate from the real objects surface. This error is caused by the fact that light is scattered in the objects volume and is not exclusively reflected at its surface. A few approaches were made to separate the surface reflected light from the volume scattered. For smooth objects the surface reflected light is dominantly concentrated in specular direction and could only be observed from a point in this direction. Thus the separation either leads to measurement results only creating data for near specular directions or provides data from not well separated areas. To ensure the flexibility and precision of optical 3D measurement systems for translucent materials it is necessary to enhance the understanding of the error forming process. For this purpose a technique for simulating the 3D measurement at translucent objects is presented. A simple error model is shortly outlined and extended to an efficient simulation environment based upon ordinary raytracing methods. In comparison the results of a Monte-Carlo simulation are presented. Only a few material and object parameters are needed for the raytracing simulation approach. The attempt of in-system collection of these material and object specific parameters is illustrated. The main concept of developing an error-compensation method based on the simulation environment and the collected parameters is described. The complete procedure is using both, the surface reflected and the volume scattered light for further processing.
3-D land subsidence simulation using the NDIS package for MODFLOW
Kang, D. H.; Li, J.
2015-11-01
The standard subsidence package for MODFLOW, MODFLOW-SUB simulates aquifer-system compaction and subsidence assuming that only 1-D-vertical displacement of the aquifer system occurs in response to applied stresses such as drawdowns accompanying groundwater extraction. In the present paper, 3-D movement of an aquifer system in responses to one or more pumping wells is considered using the new aquifer-system deformation package for MODFLOW, NDIS. The simulation of aquifer- system 3-D movement using NDIS was conducted with a stress or hydraulic head dependent specific storage coefficient to simulate nonlinear deformation behavior of aquifer-system sedimentary materials. NDIS's numerical simulation for aquifer horizontal movement is consistent with an analytic solution for horizontal motion in response to pumping from a leaky confined aquifer (Li, 2007). For purposes of comparison, vertical subsidence of the aquifer system in response to groundwater pumping is simulated by the both the NDIS and MODFLOW-SUB models. The results of the simulations show that land subsidence simulated by MODFLOW-SUB is significantly larger and less sensitive to pumping rate and time than that simulated by NDIS. The NDIS simulations also suggest that if the total pumpage is the same, pumping from a single well may induce more land subsidence than pumping from multiple wells.
The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis
Purpose: This work proposes a new method of building 3D models of microcalcification clusters and describes the validation of their realistic appearance when simulated into 2D digital mammograms and into breast tomosynthesis images. Methods: A micro-CT unit was used to scan 23 breast biopsy specimens of microcalcification clusters with malignant and benign characteristics and their 3D reconstructed datasets were segmented to obtain 3D models of microcalcification clusters. These models were then adjusted for the x-ray spectrum used and for the system resolution and simulated into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. Six radiologists were asked to distinguish between 40 real and 40 simulated clusters of microcalcifications in two separate studies on 2D mammography and tomosynthesis datasets. Receiver operating characteristic (ROC) analysis was used to test the ability of each observer to distinguish between simulated and real microcalcification clusters. The kappa statistic was applied to assess how often the individual simulated and real microcalcification clusters had received similar scores (''agreement'') on their realistic appearance in both modalities. This analysis was performed for all readers and for the real and the simulated group of microcalcification clusters separately. ''Poor'' agreement would reflect radiologists' confusion between simulated and real clusters, i.e., lesions not systematically evaluated in both modalities as either simulated or real, and would therefore be interpreted as a success of the present models. Results: The area under the ROC curve, averaged over the observers, was 0.55 (95% confidence interval [0.44, 0.66]) for the 2D study, and 0.46 (95% confidence interval [0.29, 0.64]) for the tomosynthesis study, indicating no statistically significant difference between real and simulated
Simulation and laboratory test results of 3D CMS pixel detectors for HL-LHC
Alagoz, E.; Bubna, M.; Krzywda, A.; Dalla Betta, G. F.; Povoli, M.; Obertino, M. M.; Solano, A.; Vilela Pereira, A.; Arndt, K.; Bolla, G.; Bortoletto, D.; Boscardin, M.; Kwan, S.; Rivera, R.; Shipsey, I.; Uplegger, L.
2012-08-01
The CMS pixel detector is the innermost tracking device at the LHC, reconstructing interaction vertices and charged particle trajectories. The current planar sensors located in the innermost layer of the pixel detector will be exposed to very high fluences which will degrade their performances. As a possible replacement for planar pixel sensors in the High Luminosity-LHC (HL-LHC), 3D silicon technology is under consideration due to its expected good performance in harsh radiation environments. Studies are also in progress for using 3D silicon pixel detectors in near-beam proton spectrometers at the LHC. Deep Reactive Ion Etching (DRIE) plays a key role in fabricating 3D silicon detectors in which readout and ohmic electrodes are processed through the silicon substrate instead of being implanted on the silicon surface. 3D pixel devices considered in this study were processed at FBK (Trento, Italy), bump bonded to the CMS pixel readout chip, and characterized in the laboratory. Numerical simulations were also carried out. We report on selected results from laboratory measurements and TCAD simulations.
Capability of coupled 3-D neutronics/thermalhydraulic models to simulate spatial-time effects
Last advancements in computer technology made possible the incorporation on full three-dimensional reactor core model into system transient codes. Best-estimate simulations of interactions between reactor core behavior and plant dynamics have been allowed with 3D neutronics/thermalhydraulic coupled codes. Among these codes, the RELAP5-3D has been applied to the Main Steam Line Break accident to perform three-dimensional core behavior analysis. The advantage of using a 3-D neutronics/thermalhydraulic codes is more evident in the study of strongly asymmetric transient for which simple neutron point kinetic and 1-D thermalhydraulic models are not able to provide an acceptable physical representation of the phenomena that occur in the core. The main objective of this document is to demonstrate the capability to simulated complex spatial-time effects with 3-D coupled codes. Different core nodalizations and coupling schemes have been set up. This has shown that the methodology adopted and the computational tools allow accounting for different detail levels in the core representation. (author)
Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments
This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation’s lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers. IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry. This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors. (paper)
Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.
Szőke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K
2014-06-01
This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors. PMID:24727389
3D thermal modeling of TRISO fuel coupled with neutronic simulation
Hu, Jianwei [Los Alamos National Laboratory; Uddin, Rizwan [UNIV OF ILLINIOS
2010-01-01
The Very High Temperature Gas Reactor (VHTR) is widely considered as one of the top candidates identified in the Next Generation Nuclear Power-plant (NGNP) Technology Roadmap under the U.S . Depanment of Energy's Generation IV program. TRlSO particle is a common element among different VHTR designs and its performance is critical to the safety and reliability of the whole reactor. A TRISO particle experiences complex thermo-mechanical changes during reactor operation in high temperature and high burnup conditions. TRISO fuel performance analysis requires evaluation of these changes on micro scale. Since most of these changes are temperature dependent, 3D thermal modeling of TRISO fuel is a crucial step of the whole analysis package. In this paper, a 3D numerical thermal model was developed to calculate temperature distribution inside TRISO and pebble under different scenarios. 3D simulation is required because pebbles or TRISOs are always subjected to asymmetric thermal conditions since they are randomly packed together. The numerical model was developed using finite difference method and it was benchmarked against ID analytical results and also results reported from literature. Monte-Carlo models were set up to calculate radial power density profile. Complex convective boundary condition was applied on the pebble outer surface. Three reactors were simulated using this model to calculate temperature distribution under different power levels. Two asymmetric boundary conditions were applied to the pebble to test the 3D capabilities. A gas bubble was hypothesized inside the TRISO kernel and 3D simulation was also carried out under this scenario. Intuition-coherent results were obtained and reported in this paper.
Characteristics of tumor and host cells in 3-D simulated microgravity environment
Chopra, V.; Dinh, T.; Wood, T.; Pellis, N.; Hannigan, E.
Co-cultures of three-dimensional (3-D) constructs of one cell type with dispersed cells of a second cell type in low-shear rotating suspension cultures in simulated microgravity environment have been used to investigate invasive properties of normal and malignant cell types. We have shown that the epithelial and endothelial cells undergo a switch in characteristics when grown in an in vitro 3-D environment, that mimics the in vivo host environment as compared with conventional two-dimensional (2-D) monolayer cultures. Histological preparations and immunohistochemical staining procedures of cocultured harvests demonstrated various markers of interest: like collagen vimentin, mucin, elastin, fibrin, fibrinogen, cytokeratin, adhesion molecules and various angiogenic factors by tumor cells from gynecological cancer patients along with fibroblasts, endothelial cells and patient-derived mononuclear cells (n=8). The growth rate was enhanced 10-15 folds by 3-D cocultures of patient-derived cells as compared with 2-D monolayer cultures and 3-D monocultures. The production of interleukin-2, interleukin-6, interleukin -8, vascular endothelial cell growth factor, basic fibroblast growth factor, and angiogenin was studied by using ELISA and RT- PCR. Human umbilical vein-derived endothelial cell (HUVEC) were used to study the mitogenic response of the conditioned medium collected from 3-D monocultures and cocultures during proliferation and migration assays. The conditioned medium collected from 3-D cocultures of cancer cells also 1) increased the expression of message levels of vascular endothelial growth factor and its receptor flt-1 and KDR was observed by HUVEC, and 2) increased the expression of intracellular and vascular cell adhesion molecules on the surface of HUVEC, when measured by using Live cell ELISA assays and immunofluorescent staining as compared with 3-D monocultures of normal epithelial cells. There was an increase in production of 1) enzymatic activity that
Clementel, N; Kruip, C J H; Icke, V; Gull, T R
2014-01-01
Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in $\\eta$ Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in $\\eta$ Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidde...
3D Simulations of MHD Jet Propagation Through Uniform and Stratified External Environments
O'Neill, S. M.; Tregillis, I. L.; Jones, T. W.; Ryu, Dongsu
2005-01-01
We present a set of high-resolution 3D MHD simulations of steady light, supersonic jets, exploring the influence of jet Mach number and the ambient medium on jet propagation and energy deposition over long distances. The results are compared to simple self-similar scaling relations for the morphological evolution of jet-driven structures and to previously published 2D simulations. For this study we simulated the propagation of light jets with internal Mach numbers 3 and 12 to lengths exceedin...
Determination of key parameters of SEU occurrence using 3-D full cell SRAM simulations
A 3-D entire SRAM cell, based on a 0.35-microm current CMOS technology, is simulated in this work with a DEVICE simulator. The transient current, resulting from a heavy ion strike in the most sensitive region of the cell, is studied as a function of the LET value, the cell layout and the ion penetration depth. A definition of the critical charge is proposed and two new methods are presented to compute this basic amount of charge only using SPICE simulations. Numerical applications are performed with two different generations of submicron CMOS technologies, including the determination of the sensitive thicknesses
The Surface of Stellar Models - Now with more 3D simulations!
Trampedach Regner
2015-01-01
Full Text Available We have constructed a grid of 3D hydrodynamic simulations of deep convective and line-blanketed atmospheres. We have developed a new consistent method for computing and employing T(τ relations from these simulations, as surface boundary conditions for 1D stellar structure models. These 1D models have, in turn, had their mixing-length, α, calibrated against the averaged structure of each of the simulations. Both α and T(τ vary significantly with Teff and log g.
3D full-loop simulation of an industrial-scale circulating fluidized boiler
Lu, Bona; Zhang, Nan; Wang, Wei; Li, Jinghai [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Multi-phase Complex Systems
2013-07-01
In this study, 3D full-loop simulations of a CFB boiler are carried out. FLUENT {sup registered} 6.3 is used as the solver, where an Eulerian multiphase model with EMMS-based drag model is employed. The wide particle size distribution are considered and divided into several groups to better represent the polydisperse behavior of ash particles. The simulation shows that, compared to the conventional drag model, EMMS-based model predicts more reasonable pressure drop of furnace and larger slip velocity at the lower elevations of the furnace. Further work is under way to improve the full-loop simulation.
3D modeling and simulation of 2G HTS stacks and coils
Use of 2G HTS coated conductors in several power applications has become popular in recent years. Their large current density under high magnetic fields makes them suitable candidates for high power capacity applications such as stacks of tapes, coils, magnets, cables and current leads. For this reason, modeling and simulation of their electromagnetic properties is very desirable in the design and optimization processes. For many applications, when symmetries allow it, simple models consisting of 1D or 2D representations are well suited for providing a satisfying description of the problem at hand. However, certain designs such as racetrack coils and finite-length or non-straight stacks, do pose a 3D problem that cannot be easily reduced to a 2D configuration. Full 3D models have been developed, but their use for simulating superconducting devices is a very challenging task involving a large-scale computational problem. In this work, we present a new method to simulate the electromagnetic transient behavior of 2G HTS stacks and coils. The method, originally used to model stacks of straight superconducting tapes or circular coils in 2D, is now extended to 3D. The main idea is to construct an anisotropic bulk-like equivalent for the stack or coil, such that the geometrical layout of the internal alternating structures of insulating, metallic, superconducting and substrate layers is reduced while keeping the overall electromagnetic behavior of the original device. Besides the aforementioned interest in modeling and simulating 2G HTS coated conductors, this work provides a further step towards efficient 3D modeling and simulation of superconducting devices for large-scale applications. (paper)
Holzreuter, R
2013-01-01
We investigate the effects of horizontal radiative transfer (RT) a NLTE on important diagnostic iron lines in a realistic 3-D HD simulation. Using a multi-level atom we compute and compare widely used Fe I line profiles at 3 different levels of approximation (3-D NLTE, 1-D NLTE, LTE). We find that the influence of horizontal RT is of the same order of magnitude as that of NLTE, although spatially more localized. Also, depending on the temperature of the surroundings, horizontal RT is found to weaken or strengthen spectral lines. Line depths and equivalent width may differ by up to 20% against the corresponding LTE value if 3-D RT is applied. Residual intensity contrasts in LTE are found to be larger than those in 3-D NLTE by up to a factor of two. When compared to 1-D NLTE, we find that horizontal RT weakens the contrast by up to 30% almost independently of the angle of line of sight. While the CLV of the 1-D and 3-D NLTE contrasts are of similar form, the LTE contrast CLV shows a different run. The determina...
On 3D simulation of moving objects in a digital earth system
2008-01-01
"How do the rescue helicopters find out an optimized path to arrive at the site of a disaster as soon as possible?" or "How are the flight procedures over mountains and plateaus simulated?" and so on.In this paper a script language on spatial moving objects is presented by abstracting 3D spatial moving objects’ behavior when implementing moving objects simulation in 3D digital Earth scene,which is based on a platform of digital China named "ChinaStar".The definition of this script language,its morphology and syntax,its compiling and mediate language generating,and the behavior and state control of spatial moving objects are discussed emphatically.In addition,the language’s applications and implementation are also discussed.
3D Kinetic Simulations of Topography-Induced Electric Fields at Itokawa Asteroid
Zimmerman, M. I.
2015-12-01
Results from a new 3D kinetic simulation code will be presented, showing how Itokawa's interaction with the solar wind plasma creates an ever-evolving electric field structure as the asteroid rotates. The simulations combine (1) a realistic surface shape model of Itokawa, (2) a careful and self-consistent accounting of surface charging processes, and (3) the freely-available FMMLib3d code library implementing the fast multipole method for electric field calculations. Fine details of the surface potential and electric grounding conditions, as revealed by this new code, could provide critical inputs into planning for a future asteroid retrieval mission in which extended, direct contact with the asteroid could occur.
Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes
Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.
2016-08-01
The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.
Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes
Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.
2016-03-01
The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.
3D COMPUTER SIMULATION FOR LIGNIFICATION OF ANCIENT CHINESE TIMBER BUILDINGS
无
2001-01-01
A pioneer research work was carried out by investigators engaged in surveying and mapping for describing ancient Chinese timber buildings by 3D frame graphs w ith a computer.Users can know the structural layers and the assembly process of the se buildings if the frame graphs are processed further with a computer model.Th is can be implemented by computer simulation technique.This technique display t he raw data on the screen of a computer and interactively manage them by combini ng technologies from computer graphics and image processing,multi-media technol ogy,artificial intelligence,highly parallel real-time computation technique an d human behavior science.This paper presents the implementing procedure of ligni fi cation simulation for large-sized wooden buildings as well as 3D dynamic assembl y of these buildings under the 3DS MAX environment.The results from computer sim ulation are also shown in the paper.
Non-crimp 3D woven composites unit cell: from geometric modelling to damage simulation
Bedogni, Enrico
2013-01-01
In the last twenty years, the research on composite materials has increased and many progresses have been made. However, there are still unresolved issues concerning the geometric modelling of a material at the meso-level (i.e. on a unit cell) and its damage simulation. In particular, the complexity of the internal geometry of some composite materials, such as 3D textiles, yields to new challenges for the research community. A correct definition of the internal structure in all the important ...
Twisting Rolls. An Heuristic Model and 3D Numerical Simulations of Vortex Patterns
Bouali, Safieddine
2003-01-01
We connect an appropriate feedback loop to a model of 2D vertical eddy of airflow which unfolds a wide range of vorticity behavior. Computational fluid dynamics of the twisted roll display a class of long lifespan 3D vortices. On the one hand, the infinitely stable columnar vortex simulated describes waterspouts and tornadoes with extended lifetime. On the other hand, a light modification of the retroaction exhibits strong similarities to tropical cyclones. Moreover, we investigate the outcom...
Pumping simulations using 3D FEM analysis on multi-pumping wells
Shuhei, KOTANI; Takahumi, KITAOKA; Makoto, NAKAMURA; Harushige, KUSUMI; 楠見, 晴重
2011-01-01
In this research, we chiefly conducted on-site measurement and analysis to examine how the pumping wells influence groundwater behavior. We established a 3D model for groundwater and make suggestions for the adequate management of the groundwater by a pumping simulation analysis. As a result, it can be seen from our research that the fluctuation of water level caused by group wells has been reproduced accurately by using our model.
3D MHD simulations of pellet injection and disruptions in tokamak plasmas
Nonlinear MHD simulation results of pellet injection show that MHD forces can accelerate large pellets, injected on the high field side of a tokamak, to the plasma center. Magnetic reconnection can produce a reverse shear q profile. Ballooning instability caused by pellets is also reduced by high field side injection. Studies are also reported of the current quench phase of disruptions, which can cause 3D halo currents and runaway electrons. (author)
3D simulation of Industrial Hall in case of fire. Benchmark between ABAQUS, ANSYS and SAFIR
Vassart, Olivier; Cajot, Louis-Guy; O'Connor, Marc; Shenkai, Y.; Fraud, C.; Zhao, Bin; De la Quintana, Jesus; Martinez de Aragon, J.; Franssen, Jean-Marc; Gens, Frederic
2004-01-01
For simple storey buildings, the structural behaviour in case of fire is relevant only for the safety of the firemen. The protection of occupants and goods is a matter of fire spread, smoke propagation, active fire fighting measures and evacuation facilities. Brittle failure, progressive collapse and partial failure of façades elements outwards may endanger the fire fighters and have to be avoided. In order to deal with such an objective, the simulation softwares has to cover the 3D structura...
BioFVM: an efficient, parallelized diffusive transport solver for 3-D biological simulations
Ghaffarizadeh, Ahmadreza; Friedman, Samuel H.; Macklin, Paul
2015-01-01
Motivation: Computational models of multicellular systems require solving systems of PDEs for release, uptake, decay and diffusion of multiple substrates in 3D, particularly when incorporating the impact of drugs, growth substrates and signaling factors on cell receptors and subcellular systems biology. Results: We introduce BioFVM, a diffusive transport solver tailored to biological problems. BioFVM can simulate release and uptake of many substrates by cell and bulk sources, diffusion and de...
The Idea and Concept of Metos3D: A Marine Ecosystem Toolkit for Optimization and Simulation in 3D
Piwonski, Jaroslaw
2014-01-01
The simulation and parameter optimization of coupled ocean circulation and ecosystem models in three space dimensions is one of the most challenging tasks in numerical climate research. Here we present a scientific toolkit that aims at supporting researchers by defining clear coupling interfaces, providing state-of-the-art numerical methods for simulation, parallelization and optimization while using only freely available and (to a great extend) platform-independent software. Besides defining a user-friendly coupling interface (API) for marine ecosystem or biogeochemical models, we heavily rely on the Portable, Extensible Toolkit for Scientific computation (PETSc) developed at Argonne Nat. Lab. for a wide variety of parallel linear and non-linear solvers and optimizers. We specifically focus on the usage of matrix-free Newton-Krylov methods for the fast computation of steady periodic solutions, and make use of the Transport Matrix Method (TMM) introduced by Khatiwala et al.
Wang, Minjie; Shen, Shuwei; Yang, Jie; Dong, Erbao; Xu, Ronald
2014-03-01
The performance of biomedical optical imaging devices heavily relies on appropriate calibration. However, many of existing calibration phantoms for biomedical optical devices are based on homogenous materials without considering the multi-layer heterogeneous structures observed in biological tissue. Using such a phantom for optical calibration may result in measurement bias. To overcome this problem, we propose a 3D printing method for freeform fabrication of tissue simulating phantoms with multilayer heterogeneous structure. The phantom simulates not only the morphologic characteristics of biological tissue but also absorption and scattering properties. The printing system is based on a 3D motion platform with coordinated control of the DC motors. A special jet nozzle is designed to mix base, scattering, and absorption materials at different ratios. 3D tissue structures are fabricated through layer-by-layer printing with selective deposition of phantom materials of different ingredients. Different mixed ratios of base, scattering and absorption materials have been tested in order to optimize the printing outcome. A spectrometer and a tissue spectrophotometer are used for characterizing phantom absorption and scattering properties. The goal of this project is to fabricate skin tissue simulating phantoms as a traceable standard for the calibration of biomedical optical spectral devices.
3D flow past transonic turbine cascade SE 1050 — Experiment and numerical simulations
Šimurda, D.; Fürst, J.; Luxa, M.
2013-08-01
This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 (known in QNET network as open test case SE1050). The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic ( M 2is = 0.8) and at transonic ( M 2is = 1.2) regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenFOAM and in-house code. Analyses of experimental data and CFD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CFD and experiments agree reasonably well.
Modeling and simulating the adaptive electrical properties of stochastic polymeric 3D networks
Memristors are passive two-terminal circuit elements that combine resistance and memory. Although in theory memristors are a very promising approach to fabricate hardware with adaptive properties, there are only very few implementations able to show their basic properties. We recently developed stochastic polymeric matrices with a functionality that evidences the formation of self-assembled three-dimensional (3D) networks of memristors. We demonstrated that those networks show the typical hysteretic behavior observed in the ‘one input-one output’ memristive configuration. Interestingly, using different protocols to electrically stimulate the networks, we also observed that their adaptive properties are similar to those present in the nervous system. Here, we model and simulate the electrical properties of these self-assembled polymeric networks of memristors, the topology of which is defined stochastically. First, we show that the model recreates the hysteretic behavior observed in the real experiments. Second, we demonstrate that the networks modeled indeed have a 3D instead of a planar functionality. Finally, we show that the adaptive properties of the networks depend on their connectivity pattern. Our model was able to replicate fundamental qualitative behavior of the real organic 3D memristor networks; yet, through the simulations, we also explored other interesting properties, such as the relation between connectivity patterns and adaptive properties. Our model and simulations represent an interesting tool to understand the very complex behavior of self-assembled memristor networks, which can finally help to predict and formulate hypotheses for future experiments. (paper)
Three-dimensional parallel UNIPIC-3D code for simulations of high-power microwave devices
Wang, Jianguo; Chen, Zaigao; Wang, Yue; Zhang, Dianhui; Liu, Chunliang; Li, Yongdong; Wang, Hongguang; Qiao, Hailiang; Fu, Meiyan; Yuan, Yuan
2010-07-01
This paper introduces a self-developed, three-dimensional parallel fully electromagnetic particle simulation code UNIPIC-3D. In this code, the electromagnetic fields are updated using the second-order, finite-difference time-domain method, and the particles are moved using the relativistic Newton-Lorentz force equation. The electromagnetic field and particles are coupled through the current term in Maxwell's equations. Two numerical examples are used to verify the algorithms adopted in this code, numerical results agree well with theoretical ones. This code can be used to simulate the high-power microwave (HPM) devices, such as the relativistic backward wave oscillator, coaxial vircator, and magnetically insulated line oscillator, etc. UNIPIC-3D is written in the object-oriented C++ language and can be run on a variety of platforms including WINDOWS, LINUX, and UNIX. Users can use the graphical user's interface to create the complex geometric structures of the simulated HPM devices, which can be automatically meshed by UNIPIC-3D code. This code has a powerful postprocessor which can display the electric field, magnetic field, current, voltage, power, spectrum, momentum of particles, etc. For the sake of comparison, the results computed by using the two-and-a-half-dimensional UNIPIC code are also provided for the same parameters of HPM devices, the numerical results computed from these two codes agree well with each other.
3D Numerical Simulation on the Sloshing Waves Excited by the Seismic Shacking
Zhang, Lin; Wu, Tso-Ren
2016-04-01
In the event of 2015 Nepal earthquake, a video clip broadcasted worldwide showed a violent water spilling in a hotel swimming pool. This sloshing phenomenon indicates a potential water loss in the sensitive facilities, e.g. the spent fuel pools in nuclear power plant, has to be taken into account carefully under the consideration of seismic-induced ground acceleration. In the previous studies, the simulation of sloshing mainly focused on the pressure force on the structure by using a simplified Spring-Mass Method developed in the field of solid mechanics. However, restricted by the assumptions of plane water surface and limited wave height, significant error will be made in evaluating the amount of water loss in the tank. In this paper, the computational fluid dynamical model, Splash3D, was adopted for studying the sloshing problem accurately. Splash3D solved 3D Navier-Stokes Equation directly with Large-Eddy Simulation (LES) turbulent closure. The Volume-of-fluid (VOF) method with piecewise linear interface calculation (PLIC) was used to track the complex breaking water surface. The time series acceleration of a design seismic was loaded to excite the water. With few restrictions from the assumptions, the accuracy of the simulation results were improved dramatically. A series model validations were conducted by compared to a 2D theoretical solution, and a 3D experimental data. Good comparisons can be seen. After the validation, we performed the simulation for considering a sloshing case in a rectangular water tank with a dimension of 12 m long, 8 m wide, 8 m deep, which contained water with 7 m in depth. The seismic movement was imported by considering time-series acceleration in three dimensions, which were about 0.5 g to 1.2 g in the horizontal directions, and 0.3 g to 1 g in the vertical direction. We focused the discussions on the kinematics of the water surface, wave breaking, velocity field, pressure field, water force on the side walls, and, most
Experimental validation of a numerical simulation on a ballscrew system by 3D photoelasticity
Germaneau A.
2010-06-01
Full Text Available The Trimmable Horizontal Stabilizer Actuator (THSA system equips the whole airbus line. One component of this system is a ball-screw system on which spalling problems appear on the balls. This phenomenon is mostly due to local high pressures and reduces the service life of the system. 3D numerical simulations are usually used to tackle this kind of problems but are subjected to assumptions. As the aim of the project is to build a numerical model able to predict pressure distribution, these assumptions need to be experimentally assessed to be perfectly relevant of the real load distribution in the ball screw system. Due to the 3D geometry of the specimen, a 3D measurement technique, Scattered Light Photoelasticity (SLP, has been chosen to perform experimental measurements,. Because of complexity of the geometry, the study is divided in three steps; the present paper is dealing with the second one where a demonstrator ball-screw system is manufactured in casted epoxy to perform the SLP. This technique gives information on 3D stress fields inside the epoxy specimen from the analysis of photoelastic fringes. They are compared to numerical ones and indicate whether numerical boundary conditions are relevant of the experimental ball-screw system behaviour.
Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like stars
Alvan, L.; Strugarek, A.; Brun, A. S.; Mathis, S.; Garcia, R. A.
2015-09-01
Context. The revolution of helio- and asteroseismology provides access to the detailed properties of stellar interiors by studying the star's oscillation modes. Among them, gravity (g) modes are formed by constructive interferences between progressive internal gravity waves (IGWs), propagating in stellar radiative zones. Our new 3D nonlinear simulations of the interior of a solar-like star allows us to study the excitation, propagation, and dissipation of these waves. Aims: The aim of this article is to clarify our understanding of the behavior of IGWs in a 3D radiative zone and to provide a clear overview of their properties. Methods: We use a method of frequency filtering that reveals the path of individual gravity waves of different frequencies in the radiative zone. Results: We are able to identify the region of propagation of different waves in 2D and 3D, to compare them to the linear raytracing theory and to distinguish between propagative and standing waves (g-modes). We also show that the energy carried by waves is distributed in different planes in the sphere, depending on their azimuthal wave number. Conclusions: We are able to isolate individual IGWs from a complex spectrum and to study their propagation in space and time. In particular, we highlight in this paper the necessity of studying the propagation of waves in 3D spherical geometry, since the distribution of their energy is not equipartitioned in the sphere.
OptogenSIM: a 3D Monte Carlo simulation platform for light delivery design in optogenetics.
Liu, Yuming; Jacques, Steven L; Azimipour, Mehdi; Rogers, Jeremy D; Pashaie, Ramin; Eliceiri, Kevin W
2015-12-01
Optimizing light delivery for optogenetics is critical in order to accurately stimulate the neurons of interest while reducing nonspecific effects such as tissue heating or photodamage. Light distribution is typically predicted using the assumption of tissue homogeneity, which oversimplifies light transport in heterogeneous brain. Here, we present an open-source 3D simulation platform, OptogenSIM, which eliminates this assumption. This platform integrates a voxel-based 3D Monte Carlo model, generic optical property models of brain tissues, and a well-defined 3D mouse brain tissue atlas. The application of this platform in brain data models demonstrates that brain heterogeneity has moderate to significant impact depending on application conditions. Estimated light density contours can show the region of any specified power density in the 3D brain space and thus can help optimize the light delivery settings, such as the optical fiber position, fiber diameter, fiber numerical aperture, light wavelength and power. OptogenSIM is freely available and can be easily adapted to incorporate additional brain atlases. PMID:26713200
Performance of dental students versus prosthodontics residents on a 3D immersive haptic simulator.
Eve, Elizabeth J; Koo, Samuel; Alshihri, Abdulmonem A; Cormier, Jeremy; Kozhenikov, Maria; Donoff, R Bruce; Karimbux, Nadeem Y
2014-04-01
This study evaluated the performance of dental students versus prosthodontics residents on a simulated caries removal exercise using a newly designed, 3D immersive haptic simulator. The intent of this study was to provide an initial assessment of the simulator's construct validity, which in the context of this experiment was defined as its ability to detect a statistically significant performance difference between novice dental students (n=12) and experienced prosthodontics residents (n=14). Both groups received equivalent calibration training on the simulator and repeated the same caries removal exercise three times. Novice and experienced subjects' average performance differed significantly on the caries removal exercise with respect to the percentage of carious lesion removed and volume of surrounding sound tooth structure removed (pimmersive haptic simulator. These results are a first step in establishing the validity of this device. PMID:24706694
Implementation of Headtracking and 3D Stereo with Unity and VRPN for Computer Simulations
Noyes, Matthew A.
2013-01-01
This paper explores low-cost hardware and software methods to provide depth cues traditionally absent in monocular displays. The use of a VRPN server in conjunction with a Microsoft Kinect and/or Nintendo Wiimote to provide head tracking information to a Unity application, and NVIDIA 3D Vision for retinal disparity support, is discussed. Methods are suggested to implement this technology with NASA's EDGE simulation graphics package, along with potential caveats. Finally, future applications of this technology to astronaut crew training, particularly when combined with an omnidirectional treadmill for virtual locomotion and NASA's ARGOS system for reduced gravity simulation, are discussed.
3D CFD simulation of hydrodynamics of a 150 MWe circulating fluidized bed boiler
Nan Zhang; Bona Lu; Wei Wang; Jinghai Li [Chinese Academy of Sciences, Beijing (China). Institute of Process Engineering
2010-08-15
An Eulerian granular multiphase model with a drag coefficient based on the energy minimization multi-scale (EMMS) model was used to perform a three-dimensional (3D), full-loop, time-dependent simulation of hydrodynamics of a 150 MWe circulating fluidized bed (CFB) boiler. Simulation results were presented in terms of the pressure profile around the whole loop of solids circulation, profiles of solids volume fraction and solids vertical velocity, as well as the non-uniform distribution of solid fluxes into two parallel cyclones.
Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels
Yun, Di; Yacout, Abdellatif M.; Stan, Marius; Bauer, Theodore H.; Wright, Arthur E.
2014-05-01
Evolution of porosity generated in metallic U-Zr fuel irradiated in fast spectrum reactors leads to changes in fuel properties and impacts important phenomena such as heat transport and constituent redistribution. The porosity is generated as a result of the accumulation of fission gases and is affected by the possible bond sodium infiltration into the fuel. Typically, the impact of porosity development on properties, such as thermal conductivity, is accounted for through empirical correlations that are dependent on porosity and infiltrated sodium fractions. Currently available simulation tools make it possible to take into account fuel 3-D porosity distributions, potentially eliminating the need for such correlations. This development allows for a more realistic representation of the porosity evolution in metallic fuel and creates a framework for truly mechanistic fuel development models. In this work, COMSOL multi-physics simulation platform is used to model 3-D porosity distributions and simulate heat transport in metallic U-10Zr fuel. Available experimental data regarding microstructural evolution of fuel that was irradiated in EBR-II and associated phase stability information are used to guide the simulation. The impact of changes in porosity characteristics on material properties is estimated and the results are compared with calculated temperature distributions. The simulations demonstrate the developed capability and importance of accounting for detailed porosity distribution features for accurate fuel performance evaluation.
Full Core 3-D Simulation of a Partial MOX LWR Core
S. Bays; W. Skerjanc; M. Pope
2009-05-01
A comparative analysis and comparison of results obtained between 2-D lattice calculations and 3-D full core nodal calculations, in the frame of MOX fuel design, was conducted. This study revealed a set of advantages and disadvantages, with respect to each method, which can be used to guide the level of accuracy desired for future fuel and fuel cycle calculations. For the purpose of isotopic generation for fuel cycle analyses, the approach of using a 2-D lattice code (i.e., fuel assembly in infinite lattice) gave reasonable predictions of uranium and plutonium isotope concentrations at the predicted 3-D core simulation batch average discharge burnup. However, it was found that the 2-D lattice calculation can under-predict the power of pins located along a shared edge between MOX and UO2 by as much as 20%. In this analysis, this error did not occur in the peak pin. However, this was a coincidence and does not rule out the possibility that the peak pin could occur in a lattice position with high calculation uncertainty in future un-optimized studies. Another important consideration in realistic fuel design is the prediction of the peak axial burnup and neutron fluence. The use of 3-D core simulation gave peak burnup conditions, at the pellet level, to be approximately 1.4 times greater than what can be predicted using back-of-the-envelope assumptions of average specific power and irradiation time.
Feasibility of the integration of CRONOS, a 3-D neutronics code, into real-time simulators
Ragusa, J.C. [CEA Saclay, Dept. de Mecanique et de Technologie, 91 - Gif-sur-Yvette (France)
2001-07-01
In its effort to contribute to nuclear power plant safety, CEA proposes the integration of an engineering grade 3-D neutronics code into a real-time plant analyser. This paper describes the capabilities of the neutronics code CRONOS to achieve a fast running performance. First, we will present current core models in simulators and explain their drawbacks. Secondly, the mean features of CRONOS's spatial-kinetics methods will be reviewed. We will then present an optimum core representation with respect to mesh size, choice of finite elements (FE) basis and execution time, for accurate results as well as the multi 1-D thermal-hydraulics (T/H) model developed to take into account 3-D effects in updating the cross-sections. A Main Steam Line Break (MSLB) End-of-Life (EOL) Hot-Zero-Power (HZP) accident will be used as an example, before we conclude with the perspectives of integrating CRONOS's 3-D core model into real-time simulators. (author)
3D Simulation of Velocity Profile of Turbulent Flow in Open Channel with Complex Geometry
Kamel, Benoumessad; Ilhem, Kriba; Ali, Fourar; Abdelbaki, Djebaili
Simulation of open channel flow or river flow presents unique challenge to numerical simulators, which is widely used in the applications of computational fluid dynamics. The prediction is extremely difficult because the flow in open channel is usually transient and turbulent, the geometry is irregular and curved, and the free-surface elevation is varying with time. The results from a 3D non-linear k- ɛ turbulence model are presented to investigate the flow structure, the velocity distribution and mass transport process in a meandering compound open channel and a straight open channel. The 3D numerical model for calculating flow is set up in cylinder coordinates in order to calculate the complex boundary channel. The finite volume method is used to disperse the governing equations and the SIMPLE algorithm is applied to acquire the coupling of velocity and pressure. The non-linear k- ɛ turbulent model has good useful value because of taking into account the anisotropy and not increasing the computational time. The main contributions of this study are developing a numerical method that can be applied to predict the flow in river bends with various bend curvatures and different width-depth ratios. This study demonstrates that the 3D non-linear k- ɛ turbulence model can be used for analyzing flow structures, the velocity distribution and pollutant transport in the complex boundary open channel, this model is applicable for real river and wetland problem.
Feasibility of the integration of CRONOS, a 3-D neutronics code, into real-time simulators
In its effort to contribute to nuclear power plant safety, CEA proposes the integration of an engineering grade 3-D neutronics code into a real-time plant analyser. This paper describes the capabilities of the neutronics code CRONOS to achieve a fast running performance. First, we will present current core models in simulators and explain their drawbacks. Secondly, the mean features of CRONOS's spatial-kinetics methods will be reviewed. We will then present an optimum core representation with respect to mesh size, choice of finite elements (FE) basis and execution time, for accurate results as well as the multi 1-D thermal-hydraulics (T/H) model developed to take into account 3-D effects in updating the cross-sections. A Main Steam Line Break (MSLB) End-of-Life (EOL) Hot-Zero-Power (HZP) accident will be used as an example, before we conclude with the perspectives of integrating CRONOS's 3-D core model into real-time simulators. (author)
Simulation domain size requirements for elastic response of 3D polycrystalline materials
Ozturk, Tugce; Stein, Clayton; Pokharel, Reeju; Hefferan, Christopher; Tucker, Harris; Jha, Sushant; John, Reji; Lebensohn, Ricardo A.; Kenesei, Peter; Suter, Robert M.; Rollett, Anthony D.
2016-01-01
A fast Fourier transform (FFT) based spectral algorithm is used to compute the full field mechanical response of polycrystalline microstructures. The field distributions in a specific region are used to determine the sensitivity of the method to the number of surrounding grains through quantification of the divergence of the field values from the largest simulation domain, as successively smaller surrounding volumes are included in the simulation. The analysis considers a mapped 3D structure where the location of interest is taken to be a particular pair of surface grains that enclose a small fatigue crack, and synthetically created statistically representative microstructures to further investigate the effect of anisotropy, loading condition, loading direction, and texture. The synthetic structures are generated via DREAM3D and the measured material is a cyclically loaded, Ni-based, low solvus high refractory (LSHR) superalloy that was characterized via 3D high energy x-ray diffraction microscopy (HEDM). Point-wise comparison of distributions in the grain pairs shows that, in order to obtain a Pearson correlation coefficient larger than 99%, the domain must extend to at least the third nearest neighbor. For an elastic FFT calculation, the stress-strain distributions are not sensitive to the shape of the domain. The main result is that convergence can be specified in terms of the number of grains surrounding a region of interest.
Lorentz boosted frame simulation of Laser wakefield acceleration in quasi-3D geometry
Yu, Peicheng; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Meyers, Michael D; Tsung, Frank S; Decyk, Viktor K; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A; Lu, Wei; Silva, Luis O; Mori, Warren B
2015-01-01
When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at $\\beta_b c$ towards the laser, which can lead to a computational speedup of $\\sim \\gamma_b^2=(1-\\beta_b^2)^{-1}$. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional problems with the computation load on the order of two dimensional $r-z$ simulations. Here, we describe how to combine the speed ups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that can be used to effectively eliminate the Numerical Cerenkov Instability (NCI) that inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simul...
Li, Zheng; Zhang, Yuwen
2016-01-01
Three-dimensional melting problems are investigated numerically with Lattice Boltzmann method (LBM). Regarding algorithm's accuracy and stability, Multiple-Relaxation-Time (MRT) models are employed to simplify the collision term in LBM. Temperature and velocity fields are solved with double distribution functions, respectively. 3-D melting problems are solved with double MRT models for the first time in this article. The key point for the numerical simulation of a melting problem is the methods to obtain the location of the melting front and this article uses interfacial tracking method. The interfacial tracking method combines advantages of both deforming and fixed grid approaches. The location of the melting front was obtained by calculating the energy balance at the solid-liquid interface. Various 3-D conduction controlled melting problems are solved firstly to verify the numerical method. Liquid fraction tendency and temperature distribution obtained from numerical methods agree with the analytical result...
This paper presents current results from work performed within the European Commission project SAFETI. The main objective of SAFETI is to develop and test an innovative 3D numerical modelling procedure that will enable the 3-D simulation of nuclear waste repositories in rock. The modelling code is called AC/DC (Adaptive Continuum/ Dis-Continuum) and is partially based on Itasca Consulting Group's Particle Flow Code (PFC). Results are presented from the laboratory validation study where algorithms and procedures have been developed and tested to allow accurate 'Models for Rock' to be produced. Preliminary results are also presented on the use of AC/DC with parallel processors and adaptive logic. During the final year of the project a detailed model of the Prototype Repository Experiment at SKB's Hard Rock Laboratory will be produced using up to 128 processors on the parallel super computing facility at Liverpool University. (authors)
The current status of the development of the technology on 3D computer simulation in Japan
The development background and property of the COSIDA, which is the 3D computer simulation system for the analysis on the dismantling procedure of the nuclear facilities in Japan was reviewed. The function of the visualization on the work area, Kinematics analysis and dismantling scenario analysis, which are the sub systems of the COSIDA, has been investigated. The physical, geometrical and radiological properties were modelled in 2D or 3D in the sub system of the visualization of the work area. In the sub system of the kinematics analysis, the command set on the basic work procedure for the control of the motion of the models at a cyber space was driven. The suitability of the command set was estimated by the application of COSIDA to the programming on the motion of the remote dismantling tools for dismantling the components of the nuclear facilities at cyber space
3D Finite Volume Simulation of Accretion Discs with Spiral Shocks
Makita, M; Makita, Makoto; Matsuda, Takuya
1998-01-01
We perform 2D and 3D numerical simulations of an accretion disc in a close binary system using the Simplified Flux vector Splitting (SFS) finite volume method. In our calculations, gas is assumed to be the ideal one, and we calculate the cases with gamma=1.01, 1.05, 1.1 and 1.2. The mass ratio of the mass losing star to the mass accreting star is unity. Our results show that spiral shocks are formed on the accretion disc in all cases. In 2D calculations we find that the smaller gamma is, the more tightly the spiral winds. We observe this trend in 3D calculations as well in somewhat weaker sense.
Young, R. P.; Collins, D.; Hazzard, J.; Heath, A. [Department of Earth Sciences, Liverpool University, 4 Brownlow street, UK-0 L69 3GP Liverpool (United Kingdom); Pettitt, W.; Baker, C. [Applied Seismology Consultants LTD, 10 Belmont, Shropshire, UK-S41 ITE Shrewsbury (United Kingdom); Billaux, D.; Cundall, P.; Potyondy, D.; Dedecker, F. [Itasca Consultants S.A., Centre Scientifique A. Moiroux, 64, chemin des Mouilles, F69130 Ecully (France); Svemar, C. [Svensk Karnbranslemantering AB, SKB, Aspo Hard Rock Laboratory, PL 300, S-57295 Figeholm (Sweden); Lebon, P. [ANDRA, Parc de la Croix Blanche, 7, rue Jean Monnet, F-92298 Chatenay-Malabry (France)
2004-07-01
This paper presents current results from work performed within the European Commission project SAFETI. The main objective of SAFETI is to develop and test an innovative 3D numerical modelling procedure that will enable the 3-D simulation of nuclear waste repositories in rock. The modelling code is called AC/DC (Adaptive Continuum/ Dis-Continuum) and is partially based on Itasca Consulting Group's Particle Flow Code (PFC). Results are presented from the laboratory validation study where algorithms and procedures have been developed and tested to allow accurate 'Models for Rock' to be produced. Preliminary results are also presented on the use of AC/DC with parallel processors and adaptive logic. During the final year of the project a detailed model of the Prototype Repository Experiment at SKB's Hard Rock Laboratory will be produced using up to 128 processors on the parallel super computing facility at Liverpool University. (authors)
Application of FUN3D Solver for Aeroacoustics Simulation of a Nose Landing Gear Configuration
Vatsa, Veer N.; Lockard, David P.; Khorrami, Mehdi R.
2011-01-01
Numerical simulations have been performed for a nose landing gear configuration corresponding to the experimental tests conducted in the Basic Aerodynamic Research Tunnel at NASA Langley Research Center. A widely used unstructured grid code, FUN3D, is examined for solving the unsteady flow field associated with this configuration. A series of successively finer unstructured grids has been generated to assess the effect of grid refinement. Solutions have been obtained on purely tetrahedral grids as well as mixed element grids using hybrid RANS/LES turbulence models. The agreement of FUN3D solutions with experimental data on the same size mesh is better on mixed element grids compared to pure tetrahedral grids, and in general improves with grid refinement.
HEXBU-3D, a three-dimensional PWR-simulator program for hexagonal fuel assemblies
HEXBU-3D is a three-dimensional nodal simulator program for PWR reactors. It is designed for a reactor core that consists of hexagonal fuel assemblies and of big follower-type control assemblies. The program solves two-group diffusion equations in homogenized fuel assembly geometry by a sophisticated nodal method. The treatment of feedback effects from xenon-poisoning, fuel temperature, moderator temperature and density and soluble boron concentration are included in the program. The nodal equations are solved by a fast two-level iteration technique and the eigenvalue can be either the effective multiplication factor or the boron concentration of the moderator. Burnup calculations are performed by tabulated sets of burnup-dependent cross sections evaluated by a cell burnup program. HEXBY-3D has been originally programmed in FORTRAN V for the UNIVAC 1108 computer, but there is also another version which is operable on the CDC CYBER 170 computer. (author)
Numerical simulations of self-propelled swimming of 3D bionic fish school
无
2009-01-01
Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.
Numerical simulations of self-propelled swimming of 3D bionic fish school
WU ChuiJie; WANG Liang
2009-01-01
Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package producedfor 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.
Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.
Idkaidek, Ashraf; Jasiuk, Iwona
2015-12-01
We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents. PMID:26530842
Correlated 3D Nanoscale Mapping and Simulation of Coupled Plasmonic Nanoparticles.
Haberfehlner, Georg; Trügler, Andreas; Schmidt, Franz P; Hörl, Anton; Hofer, Ferdinand; Hohenester, Ulrich; Kothleitner, Gerald
2015-11-11
Electron tomography in combination with electron energy-loss spectroscopy (EELS) experiments and simulations was used to unravel the interplay between structure and plasmonic properties of a silver nanocuboid dimer. The precise 3D geometry of the particles fabricated by means of electron beam lithography was reconstructed through electron tomography, and the full three-dimensional information was used as an input for simulations of energy-loss spectra and plasmon resonance maps. Excellent agreement between experiment and theory was found throughout, bringing the comparison between EELS imaging and simulations to a quantitative and correlative level. In addition, interface mode patterns, normally masked by the projection nature of a transmission microscopy investigation, could be unambiguously identified through tomographic reconstruction. This work overcomes the need for geometrical assumptions or symmetry restrictions of the sample in simulations and paves the way for detailed investigations of realistic and complex plasmonic nanostructures. PMID:26495933
Impact of 3D-model thickness on FE-simulations of microstructure
Soppa, Ewa, E-mail: ewa.soppa@mpa.uni-stuttgart.de [Materialpruefungsanstalt (MPA), University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart (Germany); Nellesen, Jens [Dortmunder Initiative zur rechnerintegrierten Fertigung (RIF) e.V., Joseph-von-Fraunhofer-Strasse 20, 44227 Dortmund (Germany); Romanova, Varvara [Institute of Strength Physics and Materials Science, SB RAS, pr. Academicheskii 2/1, 634021 Tomsk (Russian Federation); Fischer, Gottfried [Dortmunder Initiative zur rechnerintegrierten Fertigung (RIF) e.V., Joseph-von-Fraunhofer-Strasse 20, 44227 Dortmund (Germany); Crostack, Horst-Artur [Lehrstuhl fuer Qualitaetswesen (LQW), Technische Universitaet Dortmund, Joseph-von-Fraunhofer-Str. 20, 44227 Dortmund (Germany); Beckmann, Felix [GKSS-Research Center, c/o GKSS at DESY, Notkestr. 85, 22607 Hamburg (Germany)
2010-01-15
To investigate the effect of model thickness on simulated strain and stress fields in two-phase materials three-dimensional and two-dimensional finite element simulations were performed. The microstructure of the models was generated both by a stochastic procedure and by transforming computer tomograms representing the microstructure into a FE mesh (artificial and realistic models, respectively). The simulated equivalent plastic strains at the surface of the realistic model were compared to equivalent strain maps obtained by digital image correlation of SEM images. The results of this study demonstrate that 2D FE simulations generally do not describe the mechanical behaviour of two-phase materials adequately. The calculated distribution of surface strain coincides with the measured one only if the thickness of 3D model exceeds a minimum value that corresponds to microstructural length scale of the material. Therefore, the thickness should be equal or larger than this minimum to get correct results at the surface.
Modeling of Neuronal Growth In Vitro: Comparison of Simulation Tools NETMORPH and CX3D
Aćimović J
2011-01-01
Full Text Available We simulate the growth of neuronal networks using the two recently published tools, NETMORPH and CX3D. The goals of the work are (1 to examine and compare the simulation tools, (2 to construct a model of growth of neocortical cultures, and (3 to characterize the changes in network connectivity during growth, using standard graph theoretic methods. Parameters for the neocortical culture are chosen after consulting both the experimental and the computational work presented in the literature. The first (three weeks in culture are known to be a time of development of extensive dendritic and axonal arbors and establishment of synaptic connections between the neurons. We simulate the growth of networks from day 1 to day 21. It is shown that for the properly selected parameters, the simulators can reproduce the experimentally obtained connectivity. The selected graph theoretic methods can capture the structural changes during growth.
Hoffmann Alex C.
2013-05-01
Full Text Available Particle tracks in a hydrocyclone generated both experimentally by positron emission particle tracking (PEPT and numerically with Eulerian-Lagranian CFD have been studied and compared. A hydrocyclone with a cylinder-on-cone design was used in this study, the geometries used in the CFD simulations and in the experiments being identical. It is shown that it is possible to track a fast-moving particle in a hydrocyclone using PEPT with high temporal and spatial resolutions. The numerical 3-D particle trajectories were generated using the Large Eddy Simulation (LES turbulence model for the fluid and Lagrangian particle tracking for the particles. The behaviors of the particles were analyzed in detail and were found to be consistent between experiments and CFD simulations. The tracks of the particles are discussed and related to the fluid flow field visualized in the CFD simulations using the cross-sectional static pressure distribution.
Probabilistic Seismic Hazard Maps for Seattle, Washington, Based on 3D Ground-Motion Simulations
Frankel, A. D.; Stephenson, W. J.; Carver, D. L.; Williams, R. A.; Odum, J. K.; Rhea, S.
2007-12-01
We have produced probabilistic seismic hazard maps for Seattle using over 500 3D finite-difference simulations of ground motions from earthquakes in the Seattle fault zone, Cascadia subduction zone, South Whidbey Island fault, and background shallow and deep source areas. The maps depict 1 Hz response spectral accelerations with 2, 5, and 10% probabilities of being exceeded in 50 years. The simulations were used to generate site and source dependent amplification factors that are applied to rock-site attenuation relations. The maps incorporate essentially the same fault sources and earthquake recurrence times as the 2002 national seismic hazard maps. The simulations included basin surface waves and basin-edge focusing effects from a 3D model of the Seattle basin. The 3D velocity model was validated by modeling several earthquakes in the region, including the 2001 M6.8 Nisqually earthquake, that were recorded by our Seattle Urban Seismic Network and the Pacific Northwest Seismic Network. The simulations duplicate our observation that earthquakes from the south and southwest typically produce larger amplifications in the Seattle basin than earthquakes from other azimuths, relative to rock sites outside the basin. Finite-fault simulations were run for earthquakes along the Seattle fault zone, with magnitudes ranging from 6.6 to 7.2, so that the effects of rupture directivity were included. Nonlinear amplification factors for soft-soil sites of fill and alluvium were also applied in the maps. For the Cascadia subduction zone, 3D simulations with point sources at different locations along the zone were used to determine amplification factors across Seattle expected for great subduction-zone earthquakes. These new urban seismic hazard maps are based on determinations of hazard for 7236 sites with a spacing of 280 m. The maps show that the highest hazard locations for this frequency band (around 1 Hz) are soft-soil sites (fill and alluvium) within the Seattle basin and
3D hybrid and MHD/particle simulations of field-reversed configurations
A nonlinear 3D code in cylindrical geometry is being developed for the stability studies of FRC. Two numerical schemes have been implemented: a hybrid scheme with particle ions and fluid electrons, and MHD/particle scheme in which the background plasma is described by MHD equations. And energetic ions are treated via particle simulations. The MHD equations are advanced on a finite-difference mesh in a cylindrical coordinate system, while particle pushing is done on 3D Cartesian grids. Full ion dynamics is retained in order to include large-orbit effects (with s∼1), which are important for the tilt mode stabilization in FRC. Also, in contrast to the previous work, δf method is utilized to reduce numerical noise in the simulations. The code has been benchmarked against previous MHD simulation of tilting instability in FRC. It was found that rigid rotation reduces the growth rate, but does not stabilize the mode even for rotation rates equal to the Alfven time. Sheared rotation is found to be destabilizing for the velocity profile considered. Simulations with a fast ion beam with 1 % of the bulk ion density and s∼3 did not show a reduction in growth rate of the tilting instability. (author)
3D Numerical Simulation of Overbank Flow in Non-Orthogonal Curvilinear Coordinates
ZHANG Ming-liang; SHEN Yong-ming; WU Xiu-guang
2005-01-01
The velocity field in meandering compound channels with overbank flow is highly three dimensional. To date, its features have been investigated experimentally and little research has been undertaken to investigate the feasibility of reproducing these velocity fields with computer models. If computer modeling were to prove successful in this context, it could become a useful prediction technique and research tool to enhance our understanding of natural river dynamics. A 3-D k-ε turbulence hydrodynamic model in curvilinear coordinates is established to simulate the overbank flow. The body-fitted coordinate is adopted in the horizontal plane, the part grid is adopted in the vertical direction, and the wall-function method is employed to simulate the bed resistance. The model is applied to the simulation of the meandering channel with straight flood plain banks, and the main velocities and secondary velocities for both the longitudinal and cross sections are presented. Comparison and analysis show that the results of simulation are fit to reflect the results of experiment. These results show the application value of the model to 3D overbank flow.
Water flow prediction for Membranes using 3D simulations with detailed morphology
Shi, Meixia
2015-04-01
The membrane morphology significantly influences membrane performance. For osmotically driven membrane processes, the morphology strongly affects the internal concentration polarization. Different membrane morphologies were generated by simulation and their influence on membrane performance was studied, using a 3D model. The simulation results were experimentally validated for two classical phase-inversion membrane morphologies: sponge- and finger-like structures. Membrane porosity and scanning electron microscopy image information were used as model input. The permeance results from the simulation fit well the experimentally measured permeances. Water permeances were predicted for different kinds of finger-like cavity membranes with different finger-like cavity lengths and various finger-like cavity sets, as well as for membranes with cylindrical cavities. The results provide realistic information on how to increase water permeance, and also illustrate that membrane’s complete morphology is important for the accurate water permeance evaluation. Evaluations only based on porosity might be misleading, and the new 3D simulation approach gives a more realistic representation.
3D Simulation of Dam-break effect on a Solid Wall using Smoothed Particle Hydrodynamics
Suprijadi,; Naa, Christian; Putra, Anggy Trisnawan
2013-01-01
Dam is built for water supply, water flow or flooding control and electricity energy storage, but in other hand, dam is one of the most dangerous natural disaster in many countries including in Indonesia. The impact of dam break in neighbour area and is huge and many flooding in remote area, as happen in Dam Situ Gintung in Tangerang (close to Jakarta) in 2009. Smoothed Particle Hydrodynamics (SPH), is one of numerical method based on Lagrangian grid which is ap- plied in astrophysical simulation may be used to solve the simulation on dam break effect. The development of SPH methods become alternative methods to solving Navier Stokes equation, which is main key in fluid dynamic simulation. In this paper, SPH is developed for supporting solid par- ticles in use for 3D dam break effect (3D-DBE) simulation. Solid particle have been treated same as fluid particles with additional calculation for converting gained position became translation and rotation of solid object in a whole body. With this capability, the r...
Modeling simulation and visualization of conformal 3D lung tumor dosimetry
Lung tumors move during breathing depending on the patient's patho-physiological condition and orientation, thereby compromising the accurate deposition of the radiation dose during radiotherapy. In this paper, we present and validate a computer-based simulation framework to calculate the delivered dose to a 3D moving tumor and its surrounding normal tissues. The computer-based simulation framework models a 3D volumetric lung tumor and its surrounding tissues, simulates the tumor motion during a simulated dose delivery both as a self-reproducible motion and a random motion using the dose extracted from a treatment plan, and predicts the amount and location of radiation doses deposited. A radiation treatment plan of a small lung tumor (1-3 cm diameter) was developed in a commercial planning system (iPlan software, BrainLab, Munich, Germany) to simulate the radiation dose delivered. The dose for each radiation field was extracted from the software. The tumor motion was simulated for varying values of its rate, amplitude and direction within a single breath as well as from one breath to another. Such variations represent the variations in tumor motion induced by breathing variations. During the simulation of dose delivery, the dose on the target was summed to generate the real-time dose to the tumor for each beam independently. The simulation results show that the dose accumulated on the tumor varies significantly with both the tumor size and the tumor's motion rate, amplitude and direction. For a given tumor motion rate, amplitude and direction, the smaller the tumor size the smaller is the percentage of the radiation dose accumulated. The simulation results are validated by comparing the center plane of the 3D tumor with 2D film dosimetry measurements using a programmable 4D motion phantom moving in a self-reproducible pattern. The results also show the real-time capability of the framework at 40 discrete tumor motion steps per breath, which is higher than the
吴开腾; 宁建国
2003-01-01
A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.
Mochalskyy, S.; Wünderlich, D.; Ruf, B.; Franzen, P.; Fantz, U.; Minea, T.
2014-02-01
Decreasing the co-extracted electron current while simultaneously keeping negative ion (NI) current sufficiently high is a crucial issue on the development plasma source system for ITER Neutral Beam Injector. To support finding the best extraction conditions the 3D Particle-in-Cell Monte Carlo Collision electrostatic code ONIX (Orsay Negative Ion eXtraction) has been developed. Close collaboration with experiments and other numerical models allows performing realistic simulations with relevant input parameters: plasma properties, geometry of the extraction aperture, full 3D magnetic field map, etc. For the first time ONIX has been benchmarked with commercial positive ions tracing code KOBRA3D. A very good agreement in terms of the meniscus position and depth has been found. Simulation of NI extraction with different e/NI ratio in bulk plasma shows high relevance of the direct negative ion extraction from the surface produced NI in order to obtain extracted NI current as in the experimental results from BATMAN testbed.
Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like stars
Alvan, L; Brun, A S; Mathis, S; Garcia, R A
2015-01-01
The revolution of helio- and asteroseismology provides access to the detailed properties of stellar interiors by studying the star's oscillation modes. Among them, gravity (g) modes are formed by constructive interferences between progressive internal gravity waves (IGWs), propagating in stellar radiative zones. Our new 3D nonlinear simulations of the interior of a solar-like star allows us to study the excitation, propagation, and dissipation of these waves. The aim of this article is to clarify our understanding of the behavior of IGWs in a 3D radiative zone and to provide a clear overview of their properties. We use a method of frequency filtering that reveals the path of {individual} gravity waves of different frequencies in the radiative zone. We are able to identify the region of propagation of different waves in 2D and 3D, to compare them to the linear raytracing theory and to distinguish between propagative and standing waves (g modes). We also show that the energy carried by waves is distributed in d...
Gravitational Wave Signals from 3D Neutrino Hydrodynamics Simulations of Core-Collapse Supernovae
Andresen, Haakon; Mueller, Ewald; Janka, Hans-Thomas
2016-01-01
We present gravitational wave (GW) signal predictions from four 3D multi-group neutrino hydrodynamics simulations of core-collapse supernovae of progenitors with 11.2 Msun, 20 Msun, and 27 Msun. GW emission in the pre-explosion phase strongly depends on whether the post-shock flow is dominated by the standing accretion shock instability (SASI) or convection and differs considerably from 2D models. SASI activity produces a strong signal component below 250 Hz through asymmetric mass motions in the gain layer and a non-resonant coupling to the proto-neutron star (PNS). Both convection- and SASI-dominated models show GW emission above 250 Hz, but with considerably lower amplitudes than in 2D. This is due to a different excitation mechanism for high-frequency l=2 motions in the PNS surface, which are predominantly excited by PNS convection in 3D. Resonant excitation of high-frequency surface g-modes in 3D by mass motions in the gain layer is suppressed compared to 2D because of smaller downflow velocities and a l...
RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.
Pasipoularides, Ares D; Shu, Ming; Womack, Michael S; Shah, Ashish; Von Ramm, Olaf; Glower, Donald D
2003-01-01
We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts. PMID:12388220
A 3D technique for simulation of irregular electron treatment fields using a digital camera
Cerrobend inserts, which define electron field apertures, are manufactured at our institution using perspex templates. Contours are reproduced manually on these templates at the simulator from the field outlines drawn on the skin or mask of a patient. A previously reported technique for simulation of electron treatment fields uses a digital camera to eliminate the need for such templates. However, avoidance of the image distortions introduced by non-flat surfaces on which the electron field outlines were drawn could only be achieved by limiting the application of this technique to surfaces which were flat or near flat. We present a technique that employs a digital camera and allows simulation of electron treatment fields contoured on an anatomical surface of an arbitrary three-dimensional (3D) shape, such as that of the neck, extremities, face, or breast. The procedure is fast, accurate, and easy to perform
3D printing of tissue-simulating phantoms as a traceable standard for biomedical optical measurement
Dong, Erbao; Wang, Minjie; Shen, Shuwei; Han, Yilin; Wu, Qiang; Xu, Ronald
2016-01-01
Optical phantoms are commonly used to validate and calibrate biomedical optical devices in order to ensure accurate measurement of optical properties in biological tissue. However, commonly used optical phantoms are based on homogenous materials that reflect neither optical properties nor multi-layer heterogeneities of biological tissue. Using these phantoms for optical calibration may result in significant bias in biological measurement. We propose to characterize and fabricate tissue simulating phantoms that simulate not only the multi-layer heterogeneities but also optical properties of biological tissue. The tissue characterization module detects tissue structural and functional properties in vivo. The phantom printing module generates 3D tissue structures at different scales by layer-by-layer deposition of phantom materials with different optical properties. The ultimate goal is to fabricate multi-layer tissue simulating phantoms as a traceable standard for optimal calibration of biomedical optical spectral devices.
Pathways for Observing Stellar Surfaces Using 3D Hydrodynamical Simulations of Evolved Stars
Chiavassa, A
2015-01-01
Evolved stars are among the largest and brightest stars and they are ideal targets for the new generation of sensitive, high resolution instrumentation that provides spectrophotometric, interferometric, astrometric, and imaging observables. The interpretation of the complex stellar surface images requires numerical simulations of stellar convection that take into account multi-dimensional time-dependent radiation hydrodynamics with realistic input physics. We show how the evolved star simulations are obtained using the radiative hydrodynamics code CO5BOLD and how the accurate observables are computed with the post-processing radiative transfer code Optim3D. The synergy between observations and theoretical work is supported by a proper and quantitative analysis using these simulations, and by strong constraints from the observational side.
Detecting drug use in adolescents using a 3D simulation program
Luis Iribarne
2010-11-01
Full Text Available This work presents a new 3D simulation program, called MiiSchool, and its application to the detection of problem behaviours appearing in school settings. We begin by describing some of the main features of the Mii School program. Then, we present the results of a study in which adolescents responded to Mii School simulations involving the consumption of alcoholic drinks, cigarettes, cannabis, cocaine, and MDMA (ecstasy. We established a“risk profile” based on the observed response patterns. We also present results concerning user satisfaction with the program and the extent to which users felt that the simulated scenes were realistic. Lastly, we discuss the usefulness of Mii School as a tool for assessing drug use in school settings.
hp-HGS strategy for inverse 3D DC resistivity logging measurement simulations
Gajda-Zaǵorska, Ewa
2012-06-02
In this paper we present a twin adaptive strategy hp-HGS for solving inverse problems related to 3D DC borehole resistivity measurement simulations. The term “simulation of measurements” is widely used by the geophysical community. A quantity of interest, voltage, is measured at a receiver electrode located in the logging instrument. We use the self-adaptive goal-oriented hp-Finite Element Method (hp-FEM) computer simulations of the process of measurements in deviated wells (when the angle between the borehole and formation layers are < 90 deg). We also employ the hierarchical genetic search (HGS) algorithm to solve the inverse problem. Each individual in the population represents a single conﬁguration of the formation layers. The evaluation of the individual is performed by solving the direct problem by means of the hp-FEM algorithm and by comparison with measured logging curve. We conclude the paper with some discussion on the parallelization of the algorithm.
ZHANG AMan; YAO XiongLiang; LI Jia; GUO Jun
2008-01-01
Based on the potential flow theory,the vortex ring is introduced to simulate the toroidal bubble,and the boundary element method is applied to simulate the evo-lution of the bubble.Elastic-plasticity of structure being taken into account,the interaction between the bubble and the elastic-plastic structure is computed by combining the boundary element method (BEM) and the finite element method (FEM),and a corresponding 3D computing program is developed.This program is used to simulate the three-dimensional bubble dynamics in free field,near wall and near the elastic-plastic structure,and the numerical results are compared with the existing experimental results.The error is within 10%.The effects of different boundaries upon the bubble dynamics are presented by studying the bubble dy-namics near different boundaries.
2008-01-01
Based on the potential flow theory, the vortex ring is introduced to simulate the toroidal bubble, and the boundary element method is applied to simulate the evo- lution of the bubble. Elastic-plasticity of structure being taken into account, the interaction between the bubble and the elastic-plastic structure is computed by combining the boundary element method (BEM) and the finite element method (FEM), and a corresponding 3D computing program is developed. This program is used to simulate the three-dimensional bubble dynamics in free field, near wall and near the elastic-plastic structure, and the numerical results are compared with the existing experimental results. The error is within 10%. The effects of different boundaries upon the bubble dynamics are presented by studying the bubble dy- namics near different boundaries.
3D Hydrodynamic Simulations of the Galactic Supernova Remnant CTB 109
Bolte, Jan; Breitschwerdt, Dieter
2015-01-01
Using detailed 3D hydrodynamic simulations we study the nature of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0), which is well-known for its semicircular shape and a bright diffuse X-ray emission feature inside the SNR. Our model has been designed to explain the observed morphology, with a special emphasis on the bright emission feature inside the SNR. Moreover, we determine the age of the remnant and compare our findings with X-ray observations. With CTB 109 we test a new method of detailed numerical simulations of diffuse young objects, using realistic initial conditions derived directly from observations. We performed numerical 3D simulations with the RAMSES code. The initial density structure has been directly taken from $^{12}$CO emission data, adding an additional dense cloud, which, when it is shocked, causes the bright emission feature. From parameter studies we obtained the position $(\\ell , b)=(109.1545^\\circ , -1.0078^\\circ)$ for an elliptical cloud with $n_\\text{cloud}=25~\\text{cm}^{-3...
3D simulations of globules and pillars formation around HII regions: turbulence and shock curvature
Tremblin, P; Minier, V; Schmidt, W; Schneider, N
2012-01-01
We investigate the interplay between the ionization radiation from massive stars and the turbulence inside the surrounding molecular gas thanks to 3D numerical simulations. We used the 3D hydrodynamical code HERACLES to model an initial turbulent medium that is ionized and heated by an ionizing source. Three different simulations are performed with different mean Mach numbers (1, 2 and 4). A non-equilibrium model for the ionization and the associated thermal processes was used. This revealed to be crucial when turbulent ram pressure is of the same order as the ionized-gas pressure. The density structures initiated by the turbulence cause local curvatures of the dense shell formed by the ionization compression. When the curvature of the shell is sufficient, the shell collapse on itself to form a pillar while a smaller curvature leads to the formation of dense clumps that are accelerated with the shell and therefore remain in the shell during the simulation. When the turbulent ram pressure of the cold gas is su...
RF study and 3-D simulations of a side-coupling thermionic RF-gun
Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.
2014-02-01
A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012©. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.
RF study and 3-D simulations of a side-coupling thermionic RF-gun
Rimjaem, S., E-mail: sakhorn.rimjaem@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand); Kusoljariyakul, K.; Thongbai, C. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand)
2014-02-01
A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012{sup ©}. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.
Aeroacoustic Simulation of Nose Landing Gear on Adaptive Unstructured Grids With FUN3D
Vatsa, Veer N.; Khorrami, Mehdi R.; Park, Michael A.; Lockhard, David P.
2013-01-01
Numerical simulations have been performed for a partially-dressed, cavity-closed nose landing gear configuration that was tested in NASA Langley s closed-wall Basic Aerodynamic Research Tunnel (BART) and in the University of Florida's open-jet acoustic facility known as the UFAFF. The unstructured-grid flow solver FUN3D, developed at NASA Langley Research center, is used to compute the unsteady flow field for this configuration. Starting with a coarse grid, a series of successively finer grids were generated using the adaptive gridding methodology available in the FUN3D code. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these computations. Time-averaged and instantaneous solutions obtained on these grids are compared with the measured data. In general, the correlation with the experimental data improves with grid refinement. A similar trend is observed for sound pressure levels obtained by using these CFD solutions as input to a FfowcsWilliams-Hawkings noise propagation code to compute the farfield noise levels. In general, the numerical solutions obtained on adapted grids compare well with the hand-tuned enriched fine grid solutions and experimental data. In addition, the grid adaption strategy discussed here simplifies the grid generation process, and results in improved computational efficiency of CFD simulations.
Aeroacoustic Simulation of a Nose Landing Gear in an Open Jet Facility Using FUN3D
Vatsa, Veer N.; Lockhard, David P.; Khorrami, Mehdi R.; Carlson, Jan-Renee
2012-01-01
Numerical simulations have been performed for a partially-dressed, cavity-closed nose landing gear configuration that was tested in NASA Langley s closed-wall Basic Aerodynamic Research Tunnel (BART) and in the University of Florida s open-jet acoustic facility known as UFAFF. The unstructured-grid flow solver, FUN3D, developed at NASA Langley Research center is used to compute the unsteady flow field for this configuration. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these computations. Time-averaged and instantaneous solutions compare favorably with the measured data. Unsteady flowfield data obtained from the FUN3D code are used as input to a Ffowcs Williams-Hawkings noise propagation code to compute the sound pressure levels at microphones placed in the farfield. Significant improvement in predicted noise levels is obtained when the flowfield data from the open jet UFAFF simulations is used as compared to the case using flowfield data from the closed-wall BART configuration.
High-resolution 3D simulations of NIF ignition targets performed on Sequoia with HYDRA
Marinak, M. M.; Clark, D. S.; Jones, O. S.; Kerbel, G. D.; Sepke, S.; Patel, M. V.; Koning, J. M.; Schroeder, C. R.
2015-11-01
Developments in the multiphysics ICF code HYDRA enable it to perform large-scale simulations on the Sequoia machine at LLNL. With an aggregate computing power of 20 Petaflops, Sequoia offers an unprecedented capability to resolve the physical processes in NIF ignition targets for a more complete, consistent treatment of the sources of asymmetry. We describe modifications to HYDRA that enable it to scale to over one million processes on Sequoia. These include new options for replicating parts of the mesh over a subset of the processes, to avoid strong scaling limits. We consider results from a 3D full ignition capsule-only simulation performed using over one billion zones run on 262,000 processors which resolves surface perturbations through modes l = 200. We also report progress towards a high-resolution 3D integrated hohlraum simulation performed using 262,000 processors which resolves surface perturbations on the ignition capsule through modes l = 70. These aim for the most complete calculations yet of the interactions and overall impact of the various sources of asymmetry for NIF ignition targets. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.
Large-eddy simulation of 3-D corner separation in a linear compressor cascade
Gao, Feng; Ma, Wei; Zambonini, Gherardo; Boudet, Jérôme; Ottavy, Xavier; Lu, Lipeng; Shao, Liang
2015-01-01
The increase of the thrust/weight ratio of aircraft engines is extremely restricted by different 3-D flow loss mechanisms. One of them is the corner separation that can form at the junction between a blade suction side and a hub or shroud. In this paper, in order to further investigate the turbulent characteristics of corner separation, large-eddy simulation (LES) is conducted on a compressor cascade configuration using NACA65 blade profiles (chord based Reynolds number: 3.82 × 105), in compa...
NUMERICAL SIMULATION OF 3-D FLOW FIELD IN ARCIFORM PLUNGE POOL
无
2002-01-01
The 3-D complex turbulent flow fields in aplunge pool with arciform bottom are simulated by using thek-ε model in body-fitted coordinates. The calculated results re-veal the flow characteristics in the arciform plunge pool underthe different flood discharge conditions, which can not be easi-ly obtained in the physical model test because the measure-ment of the complex velocity is very difficult. The calculatedflow fields are helpful to understand in depth the hydrauliccharacteristics of plunge pool. The calculated and the meas-ured pressure distributions on the pool bottom are comparedand in good agreement.
DET3D - A CFD tool for simulating hydrogen combustion in nuclear reactor safety
In this paper, the CFD code DET3D is described which has been used for simulating assumed accident scenarios in nuclear reactors (fission and fusion, see e.g. [4, 5, 11]) involving hydrogen detonations in complex 3-dimensional geometries. Two validation calculations against experiments are discussed in detail: (i) a hydrogen-air detonation in a 12 m long straight tube with a truly 3-dimensional inner obstacle, and (ii) a pure radiolytic gas detonation in a 5 m long U-shaped tube at 44 bar initial pressure. (author)
Terascale direct numerical simulations of turbulent combustion using S3D
Chen, J. H.; Choudhary, A.; de Supinski, B.; DeVries, M.; Hawkes, E. R.; Klasky, S.; Liao, W. K.; Ma, K. L.; Mellor-Crummey, J.; Podhorszki, N.; Sankaran, R.; Shende, S.; Yoo, C. S.
2009-01-01
Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory
Terascale direct numerical simulations of turbulent combustion using S3D
Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory
Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.
2014-04-01
At the heart of the spectacular bipolar Homunculus nebula lies an extremely luminous (5*10^6 L_sun) colliding wind binary with a highly eccentric (e ~ 0.9), 5.54-year orbit and a total mass ~ 110 M_sun. Our closest (D ~ 2.3 kpc) and best example of a pre-hypernova environment, Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions, stellar wind-wind collisions, and massive star evolution. In order to improve our knowledge of the system, we need to generate synthetic observations and compare them with the already available and future HST/STIS data. We present initial results from full 3D radiative transfer post-processing of 3D SPH hydrodynamical simulations of the interacting winds of Eta Carinae. We use SimpleX algorithm to obtain the ionization fractions of hydrogen and helium, this results in ionization maps of both species that constrain the regions where these lines can form. These results will allow us to put constraints on the number of ionizing photons coming from the companion. This construction of synthetic observations allows us to obtain insight into the highly complex 3D flows in Eta, from the shape of the ionized volume and its resulting optical/spectral appearance.
Takahashi, M.; Kawabata, Y.; Washitani, T.; Tanaka, S.; Maeda, S.; Mimotogi, S.
2014-03-01
In progress of lithography technologies, the importance of Mask3D analysis has been emphasized because the influence of mask topography effects is not avoidable to be increased explosively. An electromagnetic filed simulation method, such as FDTD, RCWA and FEM, is applied to analyze those complicated phenomena. We have investigated Constrained Interpolation Profile (CIP) method, which is one of the Method of Characteristics (MoC), for Mask3D analysis in optical lithography. CIP method can reproduce the phase of propagating waves with less numerical error by using high order polynomial function. The restrictions of grid distance are relaxed with spatial grid. Therefore this method reduces the number of grid points in complex structure. In this paper, we study the feasibility of CIP scheme applying a non-uniform and spatial-interpolated grid to practical mask patterns. The number of grid points might be increased in complex layout and topological structure since these structures require a dense grid to remain the fidelity of each design. We propose a spatial interpolation method based on CIP method same as time-domain interpolation to reduce the number of grid points to be computed. The simulation results of two meshing methods with spatial interpolation are shown.
Quasi 3D refined simulation of flow and pollutant transport in a meandering River Reach
Li-ren Yu
2013-03-01
Full Text Available This paper reports a quasi 3D numerical simulation in a meandering river reach of the Yellow River, aiming to develop a tool for modeling turbulent flows and pollutant transport in complex natural waters. The recently built depth-averaged two-equation turbulence model, together with and models, were used to close non-simplified quasi 3D hydrodynamic fundamental governing equations. The discretized equations were solved by advanced multi-grid iterative method under non-orthogonal body-fitted coarse and fine two-levels’ grids with collocated variable arrangement. Except for steady flow and transport computation, the processes of contaminant inpouring and plume development, caused by the side-discharge from a tribytary, also have been investigated numerically. The used three closure approaches are suitable for modeling strong mixing turbulence. The established model with higher order of magnitude of transported variable provides a possibility to elevate the computational precision. Based on the developed mathematical model, a CFD (Computational Fluid Dynamics software, namely Q3drm1.0, was developed. This numerical tool focuses on the refined simulations of the steady and unsteady problems of flow and temperature/contaminant transports in complicated computational domains with the strong ability to deal with different discharge situations: side-discharge, point-source discharge/point-sink, and area-source discharge from the slope along bank. In this article, the study of side-discharge is presented only.
PIV measurement of the flow field in a domestic refrigerator model: Comparison with 3D simulations
Ben Amara, S.; Laguerre, O.; Flick, D. [UMR Genie Industriel Alimentaire (Cemagref-AgroParisTech-INRA) - Cemagref, Parc de Tourvoie, BP 44, 92185 Antony Cedex (France); Charrier-Mojtabi, M.-C.; Lartigue, B. [Universite Paul Sabatier, Laboratoire PHASE, E.A. 3208, 118 route de Narbonne, 31062 Toulouse Cedex 4 (France)
2008-12-15
PIV (particle image velocimetry) measurements of flow field due to natural convection in a parallelepipedic enclosure representing a domestic refrigerator model (scale 1) have been undertaken in order to determine the thickness of the hydrodynamic boundary layers and to study the flow motions depending on the boundary conditions applied on the vertical walls. One of the vertical walls is maintained at a negative and constant temperature either on the totality or on one part of its surface: this wall acts as the evaporator. The other walls are in contact with external air at constant temperature. The velocity measurements have been made in the symmetry plane of the enclosure. Unsteady recirculations have been observed at the bottom of the cavity. The influence of both the temperature and the dimension of the cold wall has been studied. Numerical simulations using CFD software (Fluent) have been then performed. In the numerical model, we assumed that the temperature of the evaporator is constant while an uniform global heat transfer coefficient has been used to describe the heat exchange with the external air at constant temperature. We considered laminar 3D flows and took into account the heat transfer by radiation between the different walls of the cavity. The results obtained with the 3D numerical simulations are in quite good agreement with the experimental airflow measurements using the PIV technique. (author)
3-D electromagnetic plasma particle simulations on the Intel Delta parallel computer
A three-dimensional electromagnetic PIC code has been developed on the 512 node Intel Touchstone Delta MIMD parallel computer. This code is based on the General Concurrent PIC algorithm which uses a domain decomposition to divide the computation among the processors. The 3D simulation domain can be partitioned into 1-, 2-, or 3-dimensional sub-domains. Particles must be exchanged between processors as they move among the subdomains. The Intel Delta allows one to use this code for very-large-scale simulations (i.e. over 108 particles and 106 grid cells). The parallel efficiency of this code is measured, and the overall code performance on the Delta is compared with that on Cray supercomputers. It is shown that their code runs with a high parallel efficiency of ≥ 95% for large size problems. The particle push time achieved is 115 nsecs/particle/time step for 162 million particles on 512 nodes. Comparing with the performance on a single processor Cray C90, this represents a factor of 58 speedup. The code uses a finite-difference leap frog method for field solve which is significantly more efficient than fast fourier transforms on parallel computers. The performance of this code on the 128 node Cray T3D will also be discussed
Hayek, W; Carlsson, M; Trampedach, R; Collet, R; Gudiksen, B V; Hansteen, V H; Leenaarts, J
2010-01-01
We present the implementation of a radiative transfer solver with coherent scattering in the new BIFROST code for radiative magneto-hydrodynamical (MHD) simulations of stellar surface convection. The code is fully parallelized using MPI domain decomposition, which allows for large grid sizes and improved resolution of hydrodynamical structures. We apply the code to simulate the surface granulation in a solar-type star, ignoring magnetic fields, and investigate the importance of coherent scattering for the atmospheric structure. A scattering term is added to the radiative transfer equation, requiring an iterative computation of the radiation field. We use a short-characteristics-based Gauss-Seidel acceleration scheme to compute radiative flux divergences for the energy equation. The effects of coherent scattering are tested by comparing the temperature stratification of three 3D time-dependent hydrodynamical atmosphere models of a solar-type star: without scattering, with continuum scattering only, and with bo...
Investigating the guiding of streamers in nitrogen/oxygen mixtures with 3D simulations
Teunissen, Jannis; Nijdam, Sander; Takahashi, Eiichi; Ebert, Ute
2014-10-01
Recent experiments by S. Nijdam and E. Takahashi have demonstrated that streamers can be guided by weak pre-ionization in nitrogen/oxygen mixtures, as long as there is not too much oxygen (less than 1%). The pre-ionization was created by a laser beam, and was orders of magnitude lower than the density in a streamer channel. Here, we will study the guiding of streamers with 3D numerical simulations. First, we present simulations that can be compared with the experiments and confirm that the laser pre-ionization does not introduce space charge effects by itself. Then we investigate topics as: the conditions under which guiding can occur; how photoionization reduces the guiding at higher oxygen concentrations and whether guided streamers keep their propagation direction outside the pre-ionization. JT was supported by STW Project 10755, SN by the FY2012 Researcher Exchange Program between JSPS and NWO, and ET by JSPS KAKENHI Grant Number 24560249.
3D Transient CFD Simulation of Scroll Compressors with the Tip Seal
Gao, Haiyang; Ding, Hui; Jiang, Yu
2015-08-01
A new template simulation tool is developed for scroll compressors/expanders capable of modelling tip seal leakages. This scroll template generates a high quality 3D multiblock structured mesh from user-input stationary and orbiting scroll surfaces. The mesh movement is then automatically calculated to account for every position of the orbiting scroll, maintaining good grid quality and smooth movement throughout the whole revolution. A state- of-the-art efficient CFD solver is used to solve Navier-Stokes equations, capable of simulation with both real gas and ideal gas. A case study is presented for a generic scroll compressor with refrigerant R410A. The case was run with and without the tip seal volumes. Comparisons are made to show the impact of tip seals on the compressor performance.