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MARCHING CUBES BASED FRONT TRACKING METHOD AND ITS APPLICATION TO SOME INTERFACE INSTABILITY PROBLEMS

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Journal of Hydrodynamics 2011年第5期23卷 580-588页

作者： WANG Jing-yi ZOU Jian-feng ZHENG Yao REN An-lu 不详 Department of engineering Mechanics School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China

A front tracking method based on a marching cubes isosurface extractor, which is related filter generating isosurfaces from a structured point set, is provided to achieve sharp resolution for the simulation of non-diffusive interfacial flow. Compared with the traditional topology processing procedure, the current front tracking method is easier to be implemented and presents high performance in terms of computational resources. The numerical tests for 2-D highly-shearing flows and 3-D bubbles merging process are conducted to numerically examine the performance of the current methodology for tracking interfaces between two immiscible fluids The Rayleigh-Taylor （RT） and Richtmyer-Meshkov （RM） instability problems are successfully investigated with the present marching cubes based front tracking method.

关键词： interracial flow front tracking marching cubes bubbles merging process Rayleigh-Taylor (RT) instability Richtmyer- Meshkov (RM) instability

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COHESIVE FINITE ELEMENT FORMULATION FOR MODELING FRACTURE OF SOLIDS AND ITS MASSIVE PARALLEL computation

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COHESIVE FINITE ELEMENT FORMULATION FOR MODELING FRACTURE OF...

中国力学学会学术大会'2005

作者： Zhang Jifa Zheng Yao (center for engineering and scientific computation, and College of Computer Science, zhejiang university, hangzhou 310027, china)

In recent years, considerable research work in the field of fracture mechanics has been devoted to the analysis of stationary cracks in various structural systems. While such an analysis is useful to predict the behavior of a system till the point of initiation of crack propagation, its applicability reduces during the propagation phase. However, in many cases, such as homogeneous ductile materials, layered structures, composites, there is reserved strength in the system even after crack initiation has occurred and it is expanded during propagation. Thus, design considerations call for detailed analyses and understanding of the crack growth phase to profitably make use of this reserve strength. Several investigators have contributed in providing an

关键词： cohesive element parallel computation solid fracture

AN EnaBLING ENVIRONMENT FOR MULTIDISCIPLInaRY APPLICATION SIMULATIONS

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AN ENABLING ENVIRONMENT FOR MULTIDISCIPLINARY APPLICATION SI...

中国力学学会学术大会'2005

作者： Zheng Yao Xie Lijun (center for engineering and scientific computation, and College of Computer Science, zhejiang university, hangzhou 310027, china)

A Problem Solving Environment (PSE) is a computer system that provides all the computational facilities necessary to solve a target class of problems. Typically, it can reduce the difficulty of physical simulation by utilizing user natural languages and application specific terminology, and by automating many lower level computational tasks. We define a kind of PSEs in the following formula:PSE = User interface + Enabling libraries and tools + Problem solvers + Software busCommonly, a PSE should have a friendly user interface such as nature language and graphical userinterface that can help the user to use the system in a direct and efficient manner. Enabling libraries and tools arethe most valuable parts of a PSE. They provide all the necessary assistant functions for a simulation, such asgeometric modeling, mesh generation, and scientific visualization. Problem solvers are integrated into the

关键词： parallel computing problem solving environment enabling environment

PARALLEL computation OF A MESHFREE METHOD

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PARALLEL COMPUTATION OF A MESHFREE METHOD

中国力学学会学术大会'2005

作者： Zhang Jifa Zheng Yao (center for engineering and scientific computation, and College of Computer Science,zhejiang university. hangzhou 310027, china)

Standard finite element approaches are still ineffective in handling extreme material deformation, such as cases of large deformations and moving discontinuities due to severe mesh distortion. To deal with these disadvantages, a new family of numerical methods, named meshfree methods, has been *** meshfree methods to overcome the ineffectiveness, Reproducing Kernel Particle Method (RKPM) has demonstrated its great suitability for structural analysis. This report presents applications of

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Wake structures of two spheres in tandem arrangement at various gaps for Re=300

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Progress in natural Science:Materials International 2005年第2期15卷 37-41页

作者： ZOU Jianfeng*, REN Anlu, DENG Jian and CHEN Wenqu(Department of Mechanics, zhejiang university, hangzhou 310027, china) Department of Mechanics Zhejiang University Hangzhou 310027 China

The virtual boundary method is extended to a 3D application and used to simulate the flow field of two spheres in tandem arrangement for a Reynolds number of 300. The wake structures and flow spectra at various gaps are investigated. The numerical results show that for small gaps (≈1.5), due to the mutual suppress between the wakes of the two spheres, the full flow field is stable and axisymmetric. As the gap is increased to 2.0, an asymmetric but stable flow is constructed through a certain bifurcation. The downstream wake structure is characterized by a double-thread vortex structure that comprises two slender parallel vortex tubes. The double-thread structure has a planar symmetry at gap 2.0. The hairpin-shape vortices are periodically shed from the downstream sphere at gap 2.5, but the planar symmetry persists. The vortex structures at gaps ranging from 3.0 to 4.0 are irregular and the flow field is undergoing a kind of 3D transition. It is up to the large gap 5.0 that the hairpin-shape structures are reconstructed behind the upstream and the downstream sphere, and the planar symmetry is resumed. All these numerical computations were performed on an SGI Origin3900 machine at the center for engineering and scientific computation of zhejiang university.

关键词： virtual boundary method flow past two spheres wake structure flow spectra

Direct numerical simulation of a particle-laden weak-shearing plane jet

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Progress in natural Science:Materials International 2004年第3期 55-64页

作者： XIA jun 1*, HU Guilin 2, FAN Jianren 2 and CEN Kefa 2(1. College of Computer Science, and center for engineering and scientific computation, zhejiang university, hangzhou 310027, china 2. Institute for Thermal Power engineering, College of Mechanical and Energy engineering, zhejiang university, hangzhou 310027, china) CollegeofComputerScience andCenterforEngineeringandScientificComputationZhejiangUniversityHangzhou310027China InstitutetorThermalPowerengineering CollegeofMechanicalandEnergyEngineeringZhejiangUniversityHangzhou310027China

Direct numerical simulation (DNS) has been utilized to solve numerically a two dimensional compressible weak shearing plane jet, in which the jet exit velocity and the co flow velocity are in the same magnitude (2∶1 in this paper). We also use the one way coupling method to simulate the dispersion behaviors of solid particles in various representative sizes, i.e. St =0.01, 1, 10, 100, where St is the Stokes number. We get a vorticity field with fully varicose (symmetrical) modes and the entire precise processes of the rolling up of one spanwise vortex, the pairing of two vortexes and the mixing of three vortexes. The mean longitudinal velocity ( U ) profile compares well against the experimental results. The Reynolds stress profile looks special due to the symmetrical vorticity field. The particles whose St =0.01 reproduce the vortex structures in detail, and the ones of St =1 exhibit interesting self organized behaviors and possess the most non uniform concentration field. They disperse uniformly around the single and pairing vortex kernels, while a few of them are arranged almost in a straight line in the center region of the paring vortexes, which is caused by the contribution of the border of two vortexes in the pairing process. St =10 and 100 can be treated as large particles, on which the flow field has few impacts.

关键词： direct numerical simulation (DNS) plane turbulent jets vortex structures solid particles Stokes number.

R2P:A Peer-to-Peer Transfer System Based on Role and Reputation

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R2P:A Peer-to-Peer Transfer System Based on Role and Reputat...

First International Workshop on Knowledge Discovery and Data Mining

作者： Yingjie Xia Guanghua Song Yao Zheng Mingzhe Zhu College of Computer Science and center for engineering and scientific computation zhejiang university hangzhou 310027 P.R.china

＜正＞This paper introduces R2P,a Peer-to-Peer（P2P） transfer system with role based and reputation based access control *** the combination of user authentication,organization authorization and scoring system,we solve the problem of resource piracy,user privacy and network jam,which exist in traditional P2P *** R2P system takes advantage of the X509 certificate to implement the role based access control *** assembling the artificial scoring and the automatic scoring components,the system evaluates the quantity and quality of the transfer resources,putting forward the reputation based access control *** the two policies and the adaptive P2P transfer model,the R2P system provides a secure, controllable and efficient resource transfer community.

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一种有效的SAR图像自动目标识别方法

计算机工程与应用 2009年第31期45卷 186-189页

作者：毛良瑾何丽莎解利军浙江大学工程与科学计算中心杭州310027

提出了一种有效的SAR图像中自动目标识别的方法。首先采取双阈值CFAR目标分割算法对SAR图像进行目标分割。通过对SAR图像的空间局部特征和PCA全局特征的提取,在参数学习的基础上,结合了遗传算法进行迭代优化获取分类器,实现SAR图像的自... 详细信息

提出了一种有效的SAR图像中自动目标识别的方法。首先采取双阈值CFAR目标分割算法对SAR图像进行目标分割。通过对SAR图像的空间局部特征和PCA全局特征的提取,在参数学习的基础上,结合了遗传算法进行迭代优化获取分类器,实现SAR图像的自动目标识别。该方法可以直接对原始图像进行计算,避免了基于数据特征计算所带来的问题。实验结果显示,这种基于遗传算法的自动目标识别方法对T-72和BMP2坦克进行识别,获得了较好的识别率。

关键词：自动目标识别遗传算法主成分分析双阈值CFAR分割合成孔状雷达

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SimWall:a practical user-friendly stereo tiled display wall system

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Journal of zhejiang university-Science A(Applied Physics & engineering) 2007年第4期8卷 596-604页

作者： XIE Li-jun ZHENG Yao YANG Ting-jun GAO Wen-xuan PAN Ning-he School of Computer Science and center for engineering and scientific computation Zhejiang University Hangzhou 310027 China

SimWall is a user-friendly, stereo tiled display wall system composed of 18 commodity projectors operated by a Linux graphics cluster. Collaborating together, these projectors work as a single logical display capable of giving a high-resolution show, large-scale, and passive stereo scene. In order to avoid tedious system setup and maintenance, software-based automatic geometry and photometric calibration are used. The software calibration is integrated to the system seamlessly by an on-card transform method and is transparent to users. To end-users, SimWall works just as a common PC, but provides super computing, rendering and displaying ability. In addition, SimWall has stereoscopic function that gives users a semi-immersive experience in polarized passive way. This paper presents system architecture, implementation, and other technical issues such as hardware constraints, projectors alignment, geometry and photometric calibration, implementation of passive stereo, and development of overall soft- ware environment.

关键词： Tiled display wall Stereoscopic display Multi-projectors display Parallel rendering Camera-based geometry and photometric calibration

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