共查询到19条相似文献,搜索用时 750 毫秒
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依据温度标量场与动量计算的空间和时间计算分辨率不同的特点,采用两套网格,建立多分辨率双网格并行直接求解方法,用以解决极高Ra数湍流热对流DNS模拟巨大计算工作量的难题.在两套网格的数据交换上,根据每个细网格都满足连续方程,设计了速度的守恒平移插值方法.二维极高Ra数湍流热对流的计算结果表明,采用多分辨率双网格并行直接求解方法的DNS计算,可以使计算工作量降低近一个量级.瞬时温度场显示,双网格方法的计算结果可以很好地描述极高Ra数下快速运动的小尺寸漩涡团状羽流,得到的结果与原网格一致,不同方法计算得到的传热Nu数误差不超过1%. 相似文献
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铝电解槽内湍流流动与界面波动的数值模拟 总被引:8,自引:0,他引:8
建立了模拟铝电解槽内电解液和铝熔液湍流流及两层熔液界面波动的数学模型,利用交错网格上的一种基于SIMPLE算法的改形格式,计算了280kA电解槽内两层熔液的流动状况与界面形状。 相似文献
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高密度数字视盘(HD-DVD)是一种新型蓝光存储技术,可以满足数字高清视频节目的播放要求.介绍了用于HD-DVD驱动器中的刀口法调焦方案,基于菲涅耳公式和标量衍射理论,推导了刀口法调焦的HD-DVD驱动器中聚焦误差信号与离焦量之间关系的计算模型.应用该计算模型,分析了不同离焦量时探测器上光强分布情况.计算得到的聚焦误差信号与离焦量之间的关系曲线与实验测得的“S型”曲线相一致,证明了计算模型的正确性.进一步分析了正焦点时由于记录符调制而引起的聚焦误差的干扰信号,计算结果表明这种干扰的强度小于4.5%.分析表
关键词:
光存储
刀口法
聚焦误差
标量衍射 相似文献
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《物理学报》2021,(18)
采用大涡模拟方法对横向磁场作用下导电流体Taylor-Couette湍流流动进行数值模拟,以研究其运动规律.计算模型为无限长度,半径比为1/2.雷诺数分别选取为3000和5000,磁场加载方式为全局磁场,哈特曼数取值0—50.对磁场作用下泰勒涡的演化过程、速度分布和湍动能分布进行分析,并与轴向磁场作用下泰勒涡演化过程进行对比.结果表明:磁场对流场有显著的抑制作用,扭曲的泰勒涡在横向磁场的作用下破裂成小尺度涡结构,并沿磁场方向排列;在外圆筒和垂直于磁场方向的区域,磁场抑制效果较强;随着雷诺数的增加,磁场抑制效果减弱,在流场不同区域,流动呈现出不同的特点.与轴向磁场相比,横向磁场对流场的抑制效果较弱,流场分布呈现出明显的各向异性. 相似文献
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绕翼型加速流动的数值模拟-加速度的影响 总被引:2,自引:0,他引:2
对绕30°攻角NACA 0015翼型的不可压缩加速流动进行了二维数值模拟,采用有限体积法计算了水道中4种不同加速度下绕翼型的非定常流动,最终稳定的流速都为100 mm/s,对应雷诺数为8000.给出了详细的瞬态流动结构、升力系数以及流动的演化过程,重点分析了加速度对流动结构的影响.计算结果表明启动过程和完成启动后的绕翼型流动结构复杂,其流动分离现象也明显区别于稳态过程自生和自维持的分离流动,具有明显的瞬态效应,并且启动加速度大小对流动结构和发展、漩涡强度等都有直接影响. 相似文献
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利用矢量有效折射率方法(矢量法)对光子晶体光纤基模的色散特性进行了数值模拟,并与双正交归一基矢量法以及标量有效折射率方法(标量法)的模拟结果进行了对比.发现所用矢量法的结果与双正交归一基矢量法的结果符合很好,而标量法在低空气填充率f或较高归一化波数A/λ时是一种较好的近似,在空气填充率f较高或归一化波数A/λ较低时,要得到精确的结果必须利用矢量法对光子晶体光纤的特性进行模拟.讨论了光子晶体光纤包层有效折射率与光纤结构的关系.
关键词:
光子晶体光纤
矢量法
有效折射率
色散 相似文献
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Naoyuki Amemiya Shun-ichi Murasawa Nobuya Banno Kengo Miyamoto 《Physica C: Superconductivity and its Applications》1998,310(1-4):16-29
Superconducting properties of superconducting wires as well as the influence of their composite structure and twisting should be taken into account for their numerical modeling for AC loss calculations. Furthermore, complicated electromagnetic conditions in electrical apparatuses under which superconducting wires are used influence their AC loss properties; superconducting wires carry their transport current and are exposed to the external magnetic field whose direction and magnitude vary spatially. A series of numerical models of superconducting tapes based on the finite element method has been developed. In each model, some of the above-mentioned factors that could influence the AC loss properties are taken into account. The models are formulated with the current vector potential and the scalar magnetic potential (T–Ω method). Superconducting property is given by the E–J characteristic represented by a power law. The current distributions in non-twisted and twisted superconducting tapes carrying their transport current and/or exposed to the external magnetic field are calculated with these models to estimate their AC loss. The current distribution in a short piece of superconducting tape exposed to AC magnetic field is also calculated. 相似文献
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T. Yazawa J. J. Rabbers B. ten Haken H. H. J. ten Kate Y. Yamada 《Physica C: Superconductivity and its Applications》1998,310(1-4):36-41
The current density distribution of high temperature superconducting (HTS) tapes is modeled for the combined case of an alternating self and applied magnetic field. This numerical analysis is based on the two-dimensional Poisson equation for the vector potential. A one-dimensional current (z-direction) and a one-dimensional applied field (y-direction) are assumed. The vector potential is rewritten into an equation of motion for the current density J(x,y,t). The model covers the finite thickness of the conductor and an n-power E–J relation. The magnetic field dependence of Jc is also included in this E–J relation. A time-dependent two-dimensional current distribution that is influenced by the aspect ratio of the conductor and the material properties in E=f(J,B) is calculated numerically. The numerical results are compared with the experimental results for the AC loss of a tape driven by a transport current. Finally, a total AC loss factor is given for two cases in magnetic field direction, perpendicular and parallel to the conductor broad side. 相似文献
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We have calculated the effect of a magnetic field on the evolution of angular momentum eigenfunctions of a charged particle. An additional harmonic potential is supplemented to trap the wave packet. We find the probability density of the wave function is oscillating in the radial direction with a time period determined by the strength of the effective harmonic potential. When the magnetic field is along the z direction, if the initial wave function is an eigenfunction of ${\hat{L}}_{z}$, the probability density of the particle remains axis-symmetric. While for the case of an eigenfunction of ${\hat{L}}_{x}$, it is anisotropic in the x−y plane and rotates with a time period inverse proportional to the strength of the external magnetic field. We also extend the results in a phenomenological way to the case with an external magnetic field that varies harmonically in time. 相似文献
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ZHENG Yu-Ming FUCHS Christian FAESSLER
Amand SHEKHTER
Kirril SRISAWAD Pornrad KOBDAJ
Chinorat YAN Yu-Peng 《理论物理通讯》2004,41(5):746-750
The influence of the chiral mean field on the K+ in-plane
flow in heavy ion collisions at SIS energy is investigated within covariant kaon dynamics. For the kaon mesons inside the nuclear medium a quasi-particle picture including
scalar and vector fields is adopted and compared to the standard treatment with a static potential. It is confirmed that a Lorentz force from spatial component of the vector field provides
an important contribution to the in-medium kaon dynamics and
strongly counterbalances the influence of the vector potential
on the K+ in-plane flow. The calculated results show that
the new FOPI data can be reasonably described using the
Brown & Rho parametrization, which partly takes into account
the correction of higher order contributions in the chiral
expansion. This indicates that one can abstract the information
on the kaon potential in a nuclear medium from the analysis of
the K+ in-plane flow. 相似文献
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B. Van de Wiele F. Olyslager D. De Zutter 《Journal of magnetism and magnetic materials》2010,322(4):469-476
Micromagnetic hysteresis models for large, bulk like samples are useful for the identification of relations between microscopic material properties and macroscopic magnetic behavior. To bridge the gap between the nanometer space scale of the micromagnetic theory and the large sample dimensions, time and memory efficient numerical schemes are needed. In micromagnetic computations, fast Fourier transforms (FFTs) have been widely adopted to speed up magnetostatic field computations. In this paper, two FFT schemes are compared. The first scheme evaluates the magnetostatic field directly starting from the magnetization and has a large accuracy, while in the second scheme the magnetostatic field is derived from the scalar magnetic potential resulting in a reduced accuracy but also in a CPU time reduction for a magnetostatic field evaluation to 65% and a reduction of memory requirements to 55%. The influence of the low accuracy evaluations on the simulated macroscopic hysteresis behavior is studied. Therefore, comparison is made with the influence of thermal effects in hysteresis simulations. It is found that the resulting changes in macroscopic hysteresis behavior are of the same order of magnitude as the ones obtained when thermal fluctuations are taken into account in the high accuracy computations. 相似文献
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铝基复合材料在加入颗粒相之后, 延伸率和塑性变形能力明显降低. 为改善其塑性变形能力, 通过对比强脉冲磁场冲击处理前后试样内部组织和残余应力的变化特征, 研究了磁致塑性效应对铝基复合材料塑性变形能力的影响机理. 结果表明: 当磁感应强度从2 T变化到4 T时, 铝基复合材料中位错密度显著增加, 4 T时的位错密度是未加磁场时的3.1倍; 3 T, 30个脉冲处理后的复合材料中残余应力值从未加磁场时的41 MPa减小为-1 MPa. 从原子尺度来看, 强磁场导致了磁致塑性效应, 从而引起了位错的运动, 并促进了位错的退钉扎和可移动位错数量的增加; 从材料内部整体结构变化来看, 磁场加速了材料内应力的释放速率, 降低了材料内部的残余应力, 从而改善了铝基复合材料的塑性变形能力. 相似文献
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