排序方式: 共有74条查询结果,搜索用时 15 毫秒
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针对无限长两同心圆柱间的广义Oldroyd-B流体的螺旋流,圆柱管道绕对称轴方向振荡,在自身所在的平面上沿对称轴方向做加速运动拖动流体在环形管道内做螺旋流动.采用分数微分建立流动模型,应用分数微分的Laplace变换和Hankel变换方法研究非稳态Oldroyd-B流体螺旋流动在周向和轴向的速度场和剪切力.结果表明:在t=0.5时,分数阶导数α的值越小,流体的速度衰减的越慢,β有与α相反的结果;广义二阶流体,广义Maxwell流体,牛顿流体及单圆柱管道内广义Oldroyd-B流体的螺旋流的解是该模型解的特殊形式. 相似文献
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讨论了由不同温度介质的界面张力梯度而诱导的有限厚度Marangoni对流的边界层问题.假设界面张力是温度的平方函数,下表面保持恒温,上表面的温度是水平距离的线性函数.通过坐标变换和巧妙引入小参数对速度和温度边界层控制方程组摄动渐进展开,得到了问题的解析近似解.研究了Marangoni数和Prandtl数对速度、温度边界层的影响,对相应的流动特性进行了探讨. 相似文献
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Diffusion on a spherical surface with trapping is a common phenomenon in cell biology and porous systems. In this paper, we study the diffusion dynamics in a branched spherical structure and explore the influence of the geometry of the structure on the diffusion process. The process is a spherical movement that occurs only for a fixed radius and is interspersed with a radial motion inward and outward the sphere. Two scenarios govern the transport process in the spherical cavity: free diffusion and diffusion under external velocity. The diffusion dynamics is described by using the concepts of probability density function (PDF) and mean square displacement (MSD) by Fokker-Planck equation in a spherical coordinate system. The effects of dead ends, sphere curvature, and velocity on PDF and MSD are analyzed numerically in detail. We find a transient non-Gaussian distribution and sub-diffusion regime governing the angular dynamics. The results show that the diffusion dynamics strengthens as the curvature of the spherical surface increases and an external force is exerted in the same direction of the motion. 相似文献
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