共查询到20条相似文献,搜索用时 62 毫秒
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发展了一种模拟固壁近旁轴对称Stokes流中粘性液滴的运动和变形及直接计算固壁上应力的边界积分方法.用此方法对不同的液滴-固壁初始相对间距、粘度比、表面张力和浮力联合参数以及环境流动参数情况进行了数值实验.数值结果显示,由于环境流动和浮力的作用,随着时间的推进,液滴在轴向压缩,在径向拉伸.当环境流动的作用弱于浮力作用时,随着时间的推移,液滴上升并向上弯,固壁上由液滴运动所引起的应力不断减小.当环境流动的作用强于浮力作用时,随着时间的推移,液滴变得越来越扁.在这种情形,当大初始间距时,壁面上的应力随液滴的演变而增大;当小初始间距时,由环境流动、浮力及壁面对流动的较强作用的联合影响,此应力随液滴的演变而减小.由于液滴运动所引起的壁面应力的有效作用仅限于对称轴附近的一个小范围内,且此范围随液滴与固壁的初始间距增大而增大.应力的大小随初始间距增大而大为减小.表面张力对液滴变形有阻止作用.液滴粘性会减小液滴的变形和位置迁移. 相似文献
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研究了多孔介质中带二阶滑移边界的不可压缩MHD粘性流体在可渗透指数延伸壁面上的驻点流问题.通过相似变换将描述驻点流的控制方程转换为非线性常微分方程,并利用MATLAB的bvp5c函数求解非线性问题.分析并讨论了一、二阶滑移参数,抽吸/喷注参数以及渗透参数对速度分布和壁面剪切力的影响.结果显示在多孔介质中当壁面延伸速度小于外界主流速度时,随着一阶滑移参数、二阶滑移参数绝对值、抽吸/喷注参数以及渗透参数的增大,速度增大,壁面剪切力减小且均为正数;而当壁面延伸速度大于外界主流速度时形成一个反边界层,速度减小,壁面剪切力绝对值也减小且均为负数;二阶滑移参数对速度剖面和壁面剪切力的影响略大于一阶滑移参数的影响,抽吸/喷注参数对速度剖面和壁面剪切力的影响明显大于渗透参数或磁场参数的影响. 相似文献
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《数学的实践与认识》2019,(20)
研究了具有粗糙壁面的平行板微管道内三阶流体的电磁驱动流.假设两个壁面粗糙度的形状是相位差为0或π的小振幅正弦波形状.将洛伦兹力作为体积力,利用摄动法解析求出了速度和流率的近似解.通过数值计算,结果表明随着波数或非牛顿参数的增加,壁面粗糙度对三阶流体的阻力增加.随着Hartmann数的增加,壁面粗糙度对三阶流体的阻力减小.相位差为0的壁面粗糙度对流动的阻力大于相位差为π的粗糙度对流动的阻力.当波数或Hartmann数充分大时,壁面粗糙度的相位差变得不太重要. 相似文献
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研究了两个不同的非牛顿血液流动模型:低粘性剪切简单幂律模型和低粘性剪切及粘弹性振荡流的广义Maxwell模型.同时利用这两个非牛顿模型和牛顿模型,研究了磁场中刚性和弹性直血管中血液的正弦型脉动.在生理学条件下,大动脉中血液的弹性对其流动性态似乎并不产生影响,单纯低粘性剪切模型可以逼真地模拟这种血液流动.利用高剪切幂律模型模拟弹性血管中的正弦型脉动流,发现在同一压力梯度下,与牛顿流体相比较,幂律流体的平均流率和流率变化幅度都更小.控制方程用Crank-Niclson方法求解.弹性动脉中血液受磁场作用是产生此结果的直观原因.在主动脉生物流的模拟中,与牛顿流体模型比较,发现在匹配流率曲线上,幂律模型的平均壁面剪切应力增大,峰值壁面剪切应力减小.讨论了弹性血管横切磁场时的血液流动,评估了血管形状和表面不规则等因素的影响. 相似文献
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针对当前多介质流体计算中出现的速度和压强在介质界面处产生伪振荡的问题,我们设计了一种基于非平衡态的Lax-Friedrichs格式.我们构造的算法保证了多个守恒性质:总质量和分质量守恒,总动量和总能量守恒,它还可以保证分质量非负.更重要的是它消除了速度和压强在介质界面处的伪振荡.数值例子表明这一算法是有效的. 相似文献
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ZHENG ShiJun 《分析论及其应用》2004,20(3)
Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V. 相似文献
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We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals. 相似文献
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It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary. 相似文献
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《高校应用数学学报(英文版)》2014,29(4)
正Applied Mathematics-A Journal of Chinese Universities,Series B(Appl.Math.J.Chinese Univ.,Ser.B)is a comprehensive applied mathematics journal jointly sponsored by Zhejiang University,China Society for Industrial and Applied Mathematics,and Springer-Verlag.It is a quarterly journal with 相似文献
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《数学研究及应用》2014,(6)
正Journal overview:Journal of Mathematical Research with Applications(JMRA),formerly Journal of Mathematical Research and Exposition(JMRE)created in 1981,one of the transactions of China Society for Industrial and Applied Mathematics,is a home for original research papers of the highest quality in all areas of mathematics with applications.The target audience comprises:pure and applied mathematicians,graduate students in broad fields of sciences and technology,scientists and engineers interested in mathematics. 相似文献
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A cumulative-capacitated transportation problem is studied. The supply nodes and demand nodes are each chains. Shipments from a supply node to a demand node are possible only if the pair lies in a sublattice, or equivalently, in a staircase disjoint union of rectangles, of the product of the two chains. There are (lattice) superadditive upper bounds on the cumulative flows in all leading subrectangles of each rectangle. It is shown that there is a greatest cumulative flow formed by the natural generalization of the South-West Corner Rule that respects cumulative-flow capacities; it has maximum reward when the rewards are (lattice) superadditive; it is integer if the supplies, demands and capacities are integer; and it can be calculated myopically in linear time. The result is specialized to earlier work of Hoeffding (1940), Fréchet (1951), Lorentz (1953), Hoffman (1963) and Barnes and Hoffman (1985). Applications are given to extreme constrained bivariate distributions, optimal distribution with limited one-way product substitution and, generalizing results of Derman and Klein (1958), optimal sales with age-dependent rewards and capacities.To our friend, Philip Wolfe, with admiration and affection, on the occasion of his 65th birthday.Research was supported respectively by the IBM T.J. Watson and IBM Almaden Research Centers and is a minor revision of the IBM Research Report [6]. 相似文献
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