共查询到19条相似文献,搜索用时 62 毫秒
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研究了在广义二阶流体中,由于平板在自身所在平面运动而引起的时间分数阶反常扩散速度场,以及由此所产生的应力场及涡旋层的反常扩散问题.许多经典的和前人所得到的结果,都可作为本文结果的特例而出现.例如,Wyss有关分数阶扩散方程的解;经典的Rayleigh时空相似性解;Bagley等人有关应力场和速度场之间的关系式;以及Podlubny所做的有关分数阶平板运动方程的解等.此外,还获得了许多有意义的理论结果.例如,时间分数阶扩散指数β大于广义二阶流体指数α是涡旋层生成的必要条件.涡量分布函数的建立依赖于流场该点速度剖面的时间历程, 而这种历程是可以用分数阶微积分来刻画的等. 相似文献
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分数阶扩散方程半无界混合问题的解 总被引:5,自引:1,他引:4
研究了一维半无界分数阶扩散方程具有第三类非齐次边条件的混合问题.分别给出具有第三类齐次边条件的混合问题基本解以及具有零初始条件的混合问题基本解.最后得到分数阶扩散方程半无界混合问题的求解公式. 相似文献
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提出广义分数阶单元网络, 取消了Schiessel等人所提出的分数阶单元法对参数的限制, 增加了“协调方程”, 将模型解的构造扩充到广义函数空间, 使其包含更多的具有明显物理意义的解. 应用并发展了离散求逆Laplace变换的方法, 给出了模型方程的广义解. 讨论了广义分数阶单元网络Zener, Poyinting-Thomson模型. 结果表明, 有关黏弹性材料本构方程经典的和前人所得的经典整数阶和分数阶单参数模型的所有结果均可作为本文的特例而被包括. 相似文献
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研究了一类Caputo分数阶时滞细胞神经网络模型的稳定性.通过利用分数阶微积分中的常数变分法,得到了Caputo分数阶时滞细胞神经网络解的差分形式,推导出模型的有界解和平衡点的存在性与唯一性,最后证明了神经网络的全局指数稳定性. 相似文献
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建立了有限分形介质中具有吸附效应的分数阶反应扩散积分方程.利用Lap lace变换、广义有限H ankel变换及其相应的逆变换得到了以M ittag-Leffler函数为主要形式的解析解,并研究了解的渐近性态. 相似文献
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给出并证明了函数在一点处广义二阶可导的一个充分条件,分析了二元函数在一点的广义二阶导数和二阶混合偏导数之间的关系. 相似文献
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本文研究一类不可微函数Chaney意义下的二阶广义方向导数,并得到这一类不可微问题的二阶最优性条件。 相似文献
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Theoretical analysis of the velocity field, stress field and vortex sheet of generalized second order fluid with fractional anomalous diffusion 总被引:1,自引:0,他引:1
The velocity field of generalized second order fluid with fractional anomalous diiusion caused by a plate moving impulsively
in its own plane is investigated and the anomalous diffusion problems of the stress field and vortex sheet caused by this
process are studied. Many previous and classical results can be considered as particular cases of this paper, such as the
solutions of the fractional diffusion equations obtained by Wyss; the classical Rayleigh’s time-space similarity solution;
the relationship between stress field and velocity field obtained by Bagley and co-worker and Podlubny’s results on the fractional
motion equation of a plate. In addition, a lot of significant results also are obtained. For example, the necessary condition
for causing the vortex sheet is that the time fractional diffusion index β must be greater than that of generalized second
order fluid α; the establiihment of the vorticity distribution function depends on the time history of the velocity profile
at a given point, and the time history can be described by the fractional calculus. 相似文献
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二阶流体通过径向延伸平面时滑移、黏性耗散、焦耳热对MHD流动的影响 总被引:1,自引:0,他引:1
研究了二阶导电的非Newton流体,在一个可径向放射状延伸,并伴有部分滑动表面上的流动及其热交换.部分滑移用一个无量纲的滑移因子控制,其取值范围从0(全黏着)到无穷大(全滑移).使用适当的相似变换,把待求的非线性偏微分方程转化为常微分方程.讨论了边界条件的不足,在无需增加任何边界条件下,使用有效的数值格式,求解所得到的微分方程.部分滑移、磁场交互参数以及二阶流体的参数对速度场和温度场的综合分析发现,滑移量的增加,流体的动力边界层和热边界层增厚.因为当滑移量的增加,允许更多的流体通过该平面,表面摩擦因数的数值下降,并在更高的滑移参数下,摩擦因数趋于0,即流体无黏性地通过.还研究了磁场对速度场和温度场的重要影响. 相似文献
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分析在平行自由流动的非牛顿黏弹性导电流体中,连续平展表面移动时的稳态流和热传递特性,该流动处于横向均匀磁场作用下.以二阶流体构建它的本构方程,得到了速度分布和温度断面图的数值结果.讨论了诸如黏弹性参数、磁场参数和Prandtl数等不同物理参数对诸种动量和热传递特性的影响,并给出相关图示. 相似文献
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Existence and Uniqueness of Solutions for Time-Fractional Oldroyd-B Fluid Equations with Generalized Fractional Derivatives 下载免费PDF全文
Hassan Messaoudi Abdelouaheb Ardjouni Salah Zitouni 《Journal of Nonlinear Modeling and Analysis》2024,6(1):142-151
In this paper, we study the existence and uniqueness of solutions for time-fractional Oldroyd-B fluid equations with generalized fractional derivatives. We distinguish two cases. Firstly for the linear case, we get regularity results under some hypotheses of the source function and the initial data. Secondly for the nonlinear case, we use the Banach fixed point theorem to obtain the existence and uniqueness of solutions. 相似文献
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In this paper we study the equations governing the unsteady motion of an incompressible homogeneous generalized second grade fluid subject to periodic boundary conditions. We establish the existence of global-in-time strong solutions for shear thickening flows in the two and three dimensional case. We also prove uniqueness of such solution without any smallness condition on the initial data or restriction on the material moduli. 相似文献
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The aim of this paper is to present the analytical solutions corresponding to two types of unsteady unidirectional flows of a generalized Oldroyd-B fluid with fractional derivative between two parallel plates. The fractional calculus approach is used in solving the problems. The velocity distributions are determined by means of discrete Laplace transform and finite Fourier sine transform. The obtained results indicate that some well known solutions for the generalized second grade fluid, the generalized Maxwell fluid as well as the ordinary Oldroyd-B fluid appear as the limiting cases of the presented results. 相似文献