3-D numerical modeling and simulation of nanoscale FinFET for the application in ULSI circuits

A complete three-dimensional numerical modeling of nanoscale FinFET including quantum-mechanical effects for the application in future ULSI circuits has been developed. The exact potential profile in the channel has been computed by obtaining a self-consistent solution of 3D Poisson–Schrödinger equation using Leibmann's iteration method. The threshold voltage shift, drain and transfer characteristics have been estimated and the results were compared with the device simulator and experimental results. The model is purely a physics based one and overcomes the major limitations of the existing 2D/3D analytical models by providing a more accurate result and this model is validated by comparing with the existing results as well as the experimental results.     

VICON程序模拟氧碘化学激光器3维喷管流场的可行性探讨

用VICON程序对化学氧碘激光器(COIL)喷管冷流场进行了3维模拟,得出的计算区几何较准确地反映了模拟装置的几何变化。主气流方向和副气流方向的分点数反映出了此2维平面内的气动特性,对不同流量的模拟结果对比分析得出穿透过度与穿透不够一样,致使主副气流混合不好。对带化学反应的情况进行了模拟,显现出副气流从喷孔出来后穿进主气流的马蹄形结构的变化过程,这些说明VICON程序可用来模拟研究COIL喷管流场特性。     

VICON程序模拟氧碘化学激光器3维喷管流场的可行性探讨

 用VICON程序对化学氧碘激光器(COIL)喷管冷流场进行了3维模拟,得出的计算区几何较准确地反映了模拟装置的几何变化。主气流方向和副气流方向的分点数反映出了此2维平面内的气动特性,对不同流量的模拟结果对比分析得出穿透过度与穿透不够一样,致使主副气流混合不好。对带化学反应的情况进行了模拟,显现出副气流从喷孔出来后穿进主气流的马蹄形结构的变化过程,这些说明VICON程序可用来模拟研究COIL喷管流场特性。     

3-D numerical analysis of EHD turbulent flow and mono-disperse charged particle transport and collection in a wire-plate ESP

The present study attempts to develop a detailed numerical approach and a simulation procedure to predict the motion of gas, ions and particles inside a simple parallel plate channel containing a single corona wire. A hybrid Finite Element (FEM)-Flux Corrected Transport (FCT)-Finite Volume (FVM) method is used: the FEM–FCT numerical algorithm is applied for modeling the steady-state corona discharge, while the turbulent gas flow and the particle motion under electrostatic forces are modeled using the commercial CFD code FLUENT. Calculations for the gas flow are carried out by solving the Reynolds-averaged Navier–Stokes equations and turbulence is modeled using the k–? turbulence model. An additional source term is added to the gas flow equation to include the effect of the electric field, obtained by solving a coupled system of the electric field and charge transport equations using User-Defined Functions (UDFs). The particle phase is simulated based on the Lagrangian approach, where a large number of particles is traced with their motion affected by the gas flow and electrostatic forces using the Discrete Phase Model (DPM) in FLUENT. The developed model is useful to gain insight into the particle collection phenomena that take place inside an ESP.     

A direct numerical simulation method for complex modulus of particle dispersions

We report an extension of the smoothed profile method (SPM) (Y. Nakayama, K. Kim, and R. Yamamoto, Eur. Phys. J. E 26, 361 (2008)), a direct numerical simulation method for calculating the complex modulus of the dispersion of particles, in which we introduce a temporally oscillatory external force into the system. The validity of the method was examined by evaluating the storage G’(w \omega) and loss G”(w \omega) moduli of a system composed of identical spherical particles dispersed in an incompressible Newtonian host fluid at volume fractions of F \Phi = 0 , 0.41, 0.46, and 0.51. The moduli were evaluated at several frequencies of shear flow; the shear flow used here has a zigzag profile, as is consistent with the usual periodic boundary conditions. The simulation results were compared with several experiments for colloidal dispersions of spherical particles.     

High resolution numerical simulation of the structure of 2-D gaseous detonations

Two dimensional numerical simulation of the structure of gaseous detonation is investigated by utilizing the single step Arrhenius kinetic reaction mechanism in both high and low activation energy mixtures, characterized by their irregular and regular detonation structure, respectively. All the computations are performed on a small Beowulf cluster with six nodes. The dependency of the structure on the grid resolution is performed and it is found that, resolution of more than 300 cells per hrl is required to demonstrate the role of hydrodynamic instabilities, (KH and RM instabilities) in detonation propagation in irregular structures, while due to the absence of fine-scale structures, resolution of 50 cells per hrl, gives the physical structure of detonation with regular structures. Results show that the transverse waves in irregular structure are significantly stronger than the transverse wave in regular structure detonation, which can enhance the burning rate of the unburned pockets behind the shock front. Results for resolution of 600 cells per hrl illustrate that, in addition to the primary mode, the interaction of large vortices with the shock front provides secondary modes in the structure which leads to the irregularity of the structure in high activation energy mixture. In contrast with the results obtained for regular structure, which no unburned gas pockets and vortices observed behind the front, the results for irregular structure reveal that most portions of the gases, escape from shock compression and create large unburned gas pockets behind the both weak section of the Mach stem and the incident wave, which will burn eventually by the turbulent mixing due to the vortices associated with hydrodynamic instabilities. Therefore, the ignition mechanism in irregular structure is due to the both shock compression and by turbulent mixing associated with hydrodynamic instabilities, while the shock compression yields the ignition mechanism in regular structure detonation.     

磁绝缘线振荡器中高阶模式的3维数值模拟

为了解高频MILO实验中高阶模频频出现的原因并考察其对MILO器件性能的影响,利用二次开发的3维全电磁粒子模拟程序KARAT对C波段MILO器件进行了模拟研究。在存在非对称激励的情况下由束波互作用可直接导致高阶模的产生,发现了可与实验中高阶模现象比拟的高阶模,并对其中频率为4.01 GHz的模式做出判定,认为此模式是由非对称的电子和场在互作用腔中相互作用产生的高阶TM11模,并经同轴线传输转化得来。对于频率为3.67 GHz和4.53 GHz的另两高阶模目前尚不能判断。     

磁绝缘线振荡器中高阶模式的3维数值模拟

 为了解高频MILO实验中高阶模频频出现的原因并考察其对MILO器件性能的影响,利用二次开发的3维全电磁粒子模拟程序KARAT对C波段MILO器件进行了模拟研究。在存在非对称激励的情况下由束波互作用可直接导致高阶模的产生,发现了可与实验中高阶模现象比拟的高阶模,并对其中频率为4.01 GHz的模式做出判定,认为此模式是由非对称的电子和场在互作用腔中相互作用产生的高阶TM11模,并经同轴线传输转化得来。对于频率为3.67 GHz和4.53 GHz的另两高阶模目前尚不能判断。     

A 3-D simulation of a particulate dispersion

A computational study of the microstructure of strongly interacting particulate dispersions has been carried out using a force-bias Monte Carlo scheme. A cluster analysis technique has been used to investigate low-energy particle configurations. The microstructure is shown to consist of clusters containing several particles. The clusters themselves interact to form an extended network.     

激光辐照柱体铝靶的三维光滑粒子流体动力学仿真

在现有光滑粒子流体动力学方法基础上,提出了结合差分方法处理激光辐照边界条件的方法,并利用此方法自编程序模拟计算了功率密度为5.0109 W/cm2的强连续激光辐照铝靶时的热-力学效应,准确给出了与激光作用的边界粒子的分布和飞散情况,同时给出了不同时刻靶体的温度场,得到了温度分布规律,并对结果进行了分析。     

Three-dimensional effects in the modelling of ICPTs

In this paper, we numerically investigate the 3-D effects of different flow operating conditions and of complete or simplified treatments of the electromagnetic field on the characteristics of Ar and Ar/N₂ discharges in inductively coupled plasma torches working at atmospheric pressure. Simulations are performed by means of the commercial code FLUENT suitably customized to solve the electromagnetic field equations in the frame of an extended grid model. Steady state continuity, momentum and energy equations are solved for optically thin plasmas under the assumption of LTE and laminar flow. Results of parameterization on the net amount of power dissipated in the discharge, frequency of the RF generator, flow rate distribution of inlet gases and swirl velocity are presented, showing the impact of these parameters on the fluid dynamic and electromagnetic behaviour of the plasma.Received: 22 May 2003, Published online: 5 August 2003PACS: 52.75.Hn Plasma torches - 52.65.-y Plasma simulation - 52.80.Pi High-frequency and RF discharges     

三维材料微结构设计与数值模拟

为了研究材料细观尺度的力学性能与失效行为,达到对材料微结构的“性能导向型”设计与性能预测的目的,通过程序设计结合有限元数值模拟的方法实现多元多相异质体材料微观组织结构的计算机仿真、材料微结构的细观力学计算与虚拟失效分析.以材料微观组织结构计算机仿真软件ProDesign构造的多晶体材料与多晶体基复合材料微结构的代表性体积单元为基础,基于对商业有限元软件ABAQUS的二次开发,实现对材料微结构细观力学的数值计算,并根据数值模拟结果预测微结构的材料性能,识别“材料结构弱点”,评估异质体材料微结构内微裂纹的启裂 关键词： 材料微结构 数值模拟 各向异性 虚拟失效     

超音速等离子体点火过程的三维数值模拟

为了研究等离子体点燃超音速混合气流的过程,设计并验证了超音速燃烧室的三维计算模型,计算出了燃烧室等离子体点火时的流场参数和化学反应规律,分析了等离子体点火对燃烧室内燃烧的影响。计算结果表明:高温等离子体射流的滞止作用通过增加混合气在燃烧室内的停留时间提高了点火效率; 等离子体点火时燃烧区域的压力扩散比较充分,内部为压力相对平衡的低速流动; 高温等离子体射流高速射向混合气流时产生的速度矢量偏移扩大了点火面积,从而使点火效率得到提高; 氢气、空气燃烧的燃烧产物主要是水,燃烧区域局部温度主要受局部放热反应的影响。     

S波段大间隙速调管放大器输出腔的3维模拟

利用3维高频软件设计了一种用于S波段大间隙速调管的膜片加载大间隙单重入输出腔,建立了带大耦合孔的输出腔3维全结构模型,采用3维PIC程序对输出腔的提取效果进行了粒子模拟。研究结果表明：膜片加载的大间隙单重入输出腔开大耦合孔后,其所有谐振频点的场分布都不再是TM011模式,因此,在设计此类输出腔时不能以工作频点是否谐振为优化目标。提出了大间隙输出腔设计原则,根据设计原则优化后的输出腔可稳定提取1.07 GW的平均功率,提取效率约35.7%。     

Nano particle fluidisation in model 2-D and 3-D beds using high speed X-ray imaging and microtomography

Nanoparticles and nanocomposites have become a major focus of interest in science and technology due to exceptional properties they provide. However, handling and processing of ultra-fine powders is very challenging because they are extremely cohesive. Fluidization is one of techniques available to process powders. It has become increasingly important to understand how these nanoparticles can be handled and processed to benefit from their favourable properties. A high spatial (down to 400 nm) and temporal resolution (down to 1 ms) X-ray imaging apparatus has been designed to study nanoparticles in fluidized beds under different gas flow velocities. The mean volume distribution of the nanoparticle agglomerates was determined with X-ray microtomography. The X-ray microtomography technique provides valuable in situ, non-destructive structural information on the morphological changes that take place during fluidisation of powder samples.     

3维并行全电磁粒子模拟软件UNIPIC-3D

介绍了自行研制的3维并行全电磁粒子模拟软件UNIPIC-3D。在该软件中,电磁场量用二阶精度的时域有限差分方法迭代,粒子用相对论牛顿-洛仑兹力方程推进。该软件拥有复杂器件的几何建模和网格自动剖分的功能,具有模拟相对论返波管、虚阴极振荡器、磁绝缘线振荡器等高功率微波器件的能力。且该软件具有强大的后处理功能,可以显示电场、磁场、电流、电压、功率、频谱、粒子相空间等。在高性能并行计算机上对软件的并行效率进行了测试。通过与2.5维UNIPIC软件的结果进行比较,验证了UNIPIC-3D软件的正确性。     

3维并行全电磁粒子模拟软件UNIPIC-3D

介绍了自行研制的3维并行全电磁粒子模拟软件UNIPIC-3D。在该软件中,电磁场量用二阶精度的时域有限差分方法迭代,粒子用相对论牛顿-洛仑兹力方程推进。该软件拥有复杂器件的几何建模和网格自动剖分的功能,具有模拟相对论返波管、虚阴极振荡器、磁绝缘线振荡器等高功率微波器件的能力。且该软件具有强大的后处理功能,可以显示电场、磁场、电流、电压、功率、频谱、粒子相空间等。在高性能并行计算机上对软件的并行效率进行了测试。通过与2.5维UNIPIC软件的结果进行比较,验证了UNIPIC-3D软件的正确性。