共查询到20条相似文献,搜索用时 125 毫秒
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假设爆轰波阵面的法向速度是曲率的线性函数,在非结构四边形网格上采用水平集方法模拟爆轰波阵面的运动过程.水平集方程的曲率无关项采用正格式离散,曲率项采用伽辽金等参有限元方法空间离散,时间离散采用半隐格式.在笛卡儿网格和随机网格上,含曲率的水平集方程的离散格式为强一阶精度,重新初始化方程的离散格式精度为近似一阶精度.曲率收缩的不光滑界面和多个爆轰波阵面相互作用的算例说明格式可有效地模拟爆轰波与曲率相关的运动. 相似文献
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二维稳态辐射传输方程的有限差分求解法 总被引:2,自引:2,他引:0
针对扩散光学层析在小动物成像中的应用问题并基于混浊介质空间光子三维散射的实际物理效应,提出的二维稳态辐射传输方程的有限差分数值求解新方法.在此基础上,研究了不同的空间剖分网格和角度离散密度对求解准确度的影响,并通过将所提方法与蒙特卡洛模拟进行比对,验证方法的正确性.研究表明:在均匀组织体内,当离散角度达到一定数量时,由辐射传输方程的有限差分解获得的透射面和侧面的光子密度对空间网格大小并不敏感,而在反射面上光子密度计算则需要较密的空间网格才能够达到一定准确度.本研究为发展基于辐射传输方程的扩散光学层析理论奠定了基础. 相似文献
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针对扩散光学层析在小动物成像中的应用问题并基于混浊介质空间光子三维散射的实际物理效应,提出的二维稳态辐射传输方程的有限差分数值求解新方法.在此基础上,研究了不同的空间剖分网格和角度离散密度对求解准确度的影响,并通过将所提方法与蒙特卡洛模拟进行比对,验证方法的正确性.研究表明:在均匀组织体内,当离散角度达到一定数量时,由辐射传输方程的有限差分解获得的透射面和侧面的光子密度对空间网格大小并不敏感,而在反射面上光子密度计算则需要较密的空间网格才能够达到一定准确度.本研究为发展基于辐射传输方程的扩散光学层析理论奠定了基础. 相似文献
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求解Euler方程的隐式无网格算法 总被引:1,自引:1,他引:0
研究了求解Eluer方程的稳式无网格算法,用点云离散计算区域,代替通常的网格划分;在当地点云上,引入二次平方极小曲面逼近计算空间导数,用Roe的近似Riemann解确定通量;并用LU-SGS算法求解离散得到的Euler方程稳式时间后差联立方程组,数值模拟了二维翼型跨音速绕流,由于无网格算法区域离散只涉及点云,具有灵活性,适合处理复杂的气动外形。 相似文献
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在动态网格上通过耦合求解流动控制方程和结构动力学方程, 发展了一种舵面控制下飞行器运动响应过程中气动弹性数值模拟研究方法.流动控制方程采用N-S方程, 结构动力学采用线性模态叠加方法, 其中流动控制方程空间离散采用基于非结构网格的有限体积方法, 对流通量采用计算HLLC格式, 非定常时间离散采用基于LU-SGS的双时间步长方法.模拟中, 气动运动和结构变形在双时间步长方法推进过程中采用改进松耦合方法, 气动网格与结构网格之间信息交换采用无限平板样条法实现, 飞行器的运动和变形采用基于重叠网格和Delaunay图映射变形网格相结合的方法进行处理.采用多个考核算例对发展的数值方法进行考核验证, 结果表明该方法可以高效精确模拟舵面开环控制下飞行器运动响应过程中的气动弹性特性. 相似文献
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将局部基本解方法应用于静电场问题的模拟与分析。局部基本解方法是利用控制方程的基本解,基于局部理论和移动最小二乘原理提出的一种无网格算法。相比于有限元和有限差分等传统网格类方法,该方法仅需离散节点,避免了复杂的网格剖分难题。作为一种半解析数值技术,物理问题的基本解被作为插值基函数建立数值离散模型,从而保证了算法的较高精度。此外,与具有全局离散格式的无网格方法相比,局部基本解法更适用于高维复杂几何和大尺度模拟。二维和三维数值试验表明,该方法具有实施方便灵活,计算精度高和计算速度快等优势。为静电场仿真研究开辟新的途径,拓展了局部基本解方法的应用领域。 相似文献
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I. I. Antakov M. A. Moiseev E. V. Sokolov E. V. Zasypkin 《International Journal of Infrared and Millimeter Waves》1994,15(5):873-887
Using self-consistent field theory, the interaction of electron flow with HF fields in a gyroklystron has been analized. Optimal parameters of its output cavity corresponding to the maximum efficiency have been found. Experimental study of dependence of the efficiency on Q-factor and length of the output cavity has been carried out. The results of simulation are in good qualitative agreement with experimental data. 相似文献
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Analysis of Two-Phase Cavitating Flow with Two-Fluid Model Using Integrated Boltzmann Equations
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Shuhong Liu Yulin Wu Yu Xu & Hua-Shu Dou 《advances in applied mathematics and mechanics.》2013,5(5):607-638
In the present work, both computational and experimental methods are employed
to study the two-phase flow occurring in a model pump sump. The two-fluid
model of the two-phase flow has been applied to the simulation of the three-dimensional
cavitating flow. The governing equations of the two-phase cavitating flow
are derived from the kinetic theory based on the Boltzmann equation. The isotropic
RNG$k-\epsilon-k_{ca}$ turbulence model of two-phase flows in the form of cavity number instead
of the form of cavity phase volume fraction is developed. The RNG $k-\epsilon-k_{ca}$ turbulence
model, that is the RNG$k-\epsilon$ turbulence model for the liquid phase combined
with the $k_{ca}$model for the cavity phase, is employed to close the governing turbulent
equations of the two-phase flow. The computation of the cavitating flow through a
model pump sump has been carried out with this model in three-dimensional spaces.
The calculated results have been compared with the data of the PIV experiment. Good
qualitative agreement has been achieved which exhibits the reliability of the numerical
simulation model. 相似文献
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本文将电子迁移方程应用于研究空腔电离现象,证明了空腔的存在对腔内电子能谱的影响可归结为在空腔内分布一均匀电子源。导出了这一等效源谱的表示式。计算了等效电子源在平行板电离室中沉积的能量。与实验相比,明显地证实新理论比Spencer-Attix理论更好地描述了空腔电离现象。
关键词: 相似文献
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针对传统Helmholtz水声换能器设计中刚性壁假设的局限性,将Helmholtz腔体的弹性计入到液腔谐振频率计算中,实现低频弹性Helmholtz水声换能器液腔谐振频率精确设计.基于细长圆柱壳腔体的低频集中参数模型,导出了腔体弹性引入的附加声阻抗表达式,得到了弹性壁条件下Helmholtz水声换能器等效电路图,给出了考虑了末端修正的弹性壁Helmholtz共振腔液腔谐振频率计算公式.利用ANSYS软件建立了算例模型,仿真分析了不同材质、半径、长度时的Helmholtz共振腔液腔谐振频率.结果对比表明弹性理论值与仿真值符合得很好,相比起传统的刚性壁理论计算结果,本文的弹性壁理论得出的液腔谐振频率值有所降低,与真实情况更加接近.本文的结论可以为精确设计低频弹性Helmholtz水声换能器提供理论支持. 相似文献
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Good linearity and wide dynamic range are the advantages of asymmetric Fabry-Pérot (F-P) interferometric cavity, whose realization has been long for. Based on optical thin film characteristic matrix theory, an asymmetric F-P interferometric cavity with good linearity and wide dynamic range is designed. And by choosing the material of two different thin metallic layers, the asymmetric F-P interferometric cavity is successfully fabricated. The design theory and method of this asymmetric F-P interferometric cavity have been described in detailed. In this paper an asymmetric F-P interferometric cavity used in fiber optical sensor is reported. 相似文献
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A theory of creep fracture has been constructed by means of the concept and the method of nonequilibrium statistical physics. In this paper, the cavity evolution equation is given; the cavity distribution function, the cavity distribution probability, the creep fracture life of materials and the famous Monkman-Grant empirical relation are derived on the basis of the two mechanisms of the constrained cavity growth and the unconstrained cavity growth, respectively. 相似文献
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K.G. Weyer H. Wiedenmann M. Rateike W.R. Mac Gillivray P. Meystre H. Walther 《Optics Communications》1981,37(6):426-430
Using an arrangement of highly collimated sodium atomic beams in a Fabry-Perot cavity absorptive optical bistability has been observed. The response of the optically bistable system was investigated on a time scale of the order of 100 times the characteristic time of the cavity. Even so a non steady state behaviour of the system was observed. Good qualitative agreement with the two-level atom mean field radiation theory has been obtained. 相似文献
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Natural convection heat transfer in the presence of a magnetic field has received considerable attention in the past few decades because of its various applications in industrial installations. In particular, a large number of numerical studies analyzing the effect of the magnetic field on natural convection in a two-dimensional cavity have been performed. In this work, we propose to study the main characteristics of the convective heat transfer of pure fluids and nanofluids in a two-dimensional cavity differentially heated and subjected to an external magnetic field. The scale analysis method is used first to obtain a correlation giving the heat transfer rate, which is then developed to predict the behavior of the heat transfer rate for pure fluids and nanofluids. To verify the reliability of the theoretical predictions, a numerical study is also carried out. The results show that the proposed correlation predicts well the convective heat transfer characteristics obtained numerically. 相似文献