共查询到19条相似文献,搜索用时 109 毫秒
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研究了可渗透壁面上Falkner-Skan磁流体动力学(MHD)边界层流动问题.利用结合了微分变换法(DTM)和Padé近似的DTM-Padé方法,得到了边界层问题的近似解和壁摩擦因数值.通过建立一个迭代程序,边界层问题的近似解被表示为幂级数的形式,而且以图和表形式对不同参数下的近似解结果与打靶法得到的数值结果进行了对比,近似解和数值解结果高度吻合,从而验证了所得问题近似解和结论的可靠性和有效性.并且,对求得的边界层问题近似解结果进行了讨论,分析了不同物理参数对边界层流动的影响. 相似文献
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研究了运动的粘性导电流体中可渗透收缩壁面上非稳态磁流体边界层流动,利用解析和数值方法对问题进行了研究,并考虑了壁面速度滑移的影响.提出了一个新的解析方法(DTM-BF),并将其应用于求解带有无穷远边界条件的非线性控制方程的近似解析解.对所有的解析结果和数值结果进行了对比,结果显示两者非常吻合,从而证明了DTM-BF方法的有效性.另外,对不同的参数,得到了控制方程双解和单解的存在范围.最后,分别讨论了滑移参数、非稳态参数、磁场参数、抽吸/喷注参数和速度比例参数对壁面摩擦、唯一解速度分布和双解速度分布的影响. 相似文献
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研究了一类非线性强迫扰动Klein-Gordon方程.首先利用双曲正切待定系数法求得了典型的方程孤波解.然后利用泛函变分迭代原理得到了强迫扰动Klein-Gordon方程的一个近似解,并论述了解的一致有效性.所得到的近似解是一个解析式,它还可对近似解进行解析运算,而使用简单的模拟方法所得到的近似解是达不到这种效果的. 相似文献
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采用解析方法分析了矩形微通道热沉内单相稳态层流流体的流动与传热.基于y方向流速和导热不变的假设,建立流体在矩形微通道内流动的流速方程和传热的温度方程,进而推导出Nusselt数和Poiseuille数的理论表达式.通过计算结果可以看出,推导的Nusselt数和Poiseuille数的解析解与其他文献的结果吻合较好,而且当宽高比趋于无穷大时,Nusselt数和Poiseuille数分别趋近于8.235和96,这与其他文献结果完全相同.在Reynolds数相同时,摩擦因数随着宽高比的增加而增加,而在相同宽高比时,摩擦因数随Reynolds数的增加而减小. 相似文献
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非牛顿流体弹性径向渗流的自型问题的近似解 总被引:1,自引:0,他引:1
本文研究了非牛顿流体弹性径向渗流的自型解.设流体服从幂函数律.当指数n等于零时,文中得到了准确解.将此解和文献[1]的近似解作了比较.对于n>1及n<1的各种情形,文中得到了近似解.有算例. 相似文献
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本文研究幂律非牛顿流体在环管内的不定常旋转流。该方程是一非线性方程,在部分因子的稳态近似假设之下,方程被线性化,用Laplace积分变换法我们获得了问题的解。文中给出了几组解曲线,它反映了角向速度的时间演化规律与空间分布特征。另外我们专门研究了幂律指数对流场的影响,该参数的敏感性具有一定的数值界限。这一结果,在有关的工程设计中具有重要的意义。 相似文献
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The study of Heat and Mass Transfer in a Visco elastic fluid due to a continuous stretching surface using Homotopy Analysis Method 下载免费PDF全文
In this paper, an approximate analytical solution is derived for the flow velocity and temperature due to the laminar, two-dimensional flow of non-Newtonian incompressible visco elastic fluid due to a continuous stretching surface. The surface is stretched with a velocity proportional to the distance $x$ along the surface. The surface is assumed to have either power-law heat flux or power-law temperature distribution. The presence of source/sink and the effect of uniform suction and injection on the flow are considered for analysis. An approximate analytical solution has been obtained using Homotopy Analysis Method(HAM) for various values of visco elastic parameter, suction and injection rates. Optimal values of the convergence control parameters are computed for the flow variables. It was found that the computational time required for averaged residual error calculation is very very small compared to the computation time of exact squared residual errors. The effect of mass transfer parameter, visco elastic parameter, source/sink parameter and the power law index on flow variables such as velocity, temperature profiles, shear stress, heat and mass transfer rates are discussed. 相似文献
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本文利用球坐标下的Navier-Stokes方程式,采用迭代近似解法,求出了考虑流动惯性时的球面间流动的压力分布、速度分布以及流量的解析式。并利用此式可直接导出平行圆板间径向层流的相应解析表达式,它与文献[3],[4]中所提供的相应结果是完全一致的。 相似文献
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Prashant Pandey Sachin Kumar Francisco Gómez 《Mathematical Methods in the Applied Sciences》2020,43(12):7194-7207
This work presents an iterative scheme for the numerical solution of the space-time fractional two-dimensional advection–reaction–diffusion equation applying homotopy perturbation with Laplace transform using Caputo fractional-order derivatives. The solution obtained is beneficial and significant to analyze the modeling of superdiffusive systems and subdiffusive system, anomalous diffusion, transport process in porous media. This iterative technique presents the combination of homotopy perturbation technique, and Laplace transforms with He's polynomials, which can further be applied to numerous linear/nonlinear two-dimensional fractional models to computes the approximate analytical solution. In the present method, the nonlinearity can be tackle by He's polynomials. The salient features of the present scientific work are the pictorial presentations of the approximate numerical solution of the two-dimensional fractional advection–reaction–diffusion equation for different particular cases of fractional order and showcasing of the damping effect of reaction terms on the nature of probability density function of the considered two-dimensional nonlinear mathematical models for various situations. 相似文献
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Variational calculus is a differential process whereby Taylor series expansions can be developed on a term-by-term basis. Therefore, it can be used to obtain the equations which must be solved for the various-order terms arising from the application of regular perturbation theory to problems involving a small parameter. Variational calculus is summarized and applied to the approximate analytical solution of the optimal control problem. First, the various-order equations are obtained directly for a particular problem. Then, assuming that the zeroth-order solution is almost good enough, the equations for the first-order correction are obtained for the general optimal control problem and applied to the particular problem. The first-order solution is the same as the neighboring extremal for the given value of the parameter. 相似文献
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《Mathematical and Computer Modelling》2007,45(3-4):387-393
This paper presents a rigorous proof of existence and uniqueness of solutions to laminar boundary layer flow in power law non-Newtonian fluid. A theoretical estimate for skin friction coefficient is given, which is characterized by a power law exponent. The reliability and efficiency of the proposed estimate formula are verified by numerical results with a good agreement. The estimate formula can be successfully applied to give the value of the skin friction coefficient. 相似文献
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J. Arturo Mendez Navarro Elena I. Kaikina Héctor F. Ruiz Leonardo Guardado Z. Alejandro Castellanos 《Nonlinear Analysis: Real World Applications》2011,12(4):2077-2090
In this work, an analytic development for a transmission line with a corona effect for simulating an electromagnetic transient is presented. The asymptotic solution for the Radulet equations in which a nonlinear term is presented is obtained. The study is carried out for a single-phase transmission line. The electrical parameters for an overhead line are defined and several formulations for their calculation are presented. The frequency dependence of the electrical parameters is considered. In the first part, the linear problem solution is found; the Fourier and Laplace transforms are applied with respect to distance and time respectively. After finding the solution in the Fourier–Laplace domain, which is expressed in terms of a Green’s function integral, an approximate analytical solution is obtained in the distance–time domain by means of asymptotic methods. Finally, the nonlinear solution is found using as a first approach the linear solution. The results obtained show an attenuation in the voltage wave due to the corona effect. 相似文献
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Computation of approximate factors for the inverse constitutes an algebraic approach to preconditioning large and sparse linear
systems. In this paper, the aim is to combine standard preconditioning ideas with sparse approximate inverse approximation,
to have dense approximate inverse approximations (implicitly). For optimality, the approximate factoring problem is associated
with a minimization problem involving two matrix subspaces. This task can be converted into an eigenvalue problem for a Hermitian
positive semidefinite operator whose smallest eigenpairs are of interest. Because of storage and complexity constraints, the
power method appears to be the only admissible algorithm for devising sparse–sparse iterations. The subtle issue of choosing
the matrix subspaces is addressed. Numerical experiments are presented. 相似文献