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Direct numerical simulation of turbulent flows through concentric annulus with circumferential oscillation of inner wall 被引量:1
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作者 yichen yao Chunxiao XU Weixi HUANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第9期1267-1276,共10页
Periodic wall oscillations in the spanwise or circumferential direction can greatly reduce the friction drag in turbulent channel and pipe flows. In a concentric annulus, the constant rotation of the inner cylinder ca... Periodic wall oscillations in the spanwise or circumferential direction can greatly reduce the friction drag in turbulent channel and pipe flows. In a concentric annulus, the constant rotation of the inner cylinder can intensify turbulence fluctuations and enhance skin friction due to centrifugal instabilities. In the present study, the effects of the periodic oscillation of the inner wall on turbulent flows through concentric annulus are investigated by the direct numerical simulation(DNS). The radius ratio of the inner to the outer cylinders is 0.1, and the Reynolds number is 2 225 based on the bulk mean velocity Um and the half annulus gap H. The influence of oscillation period is considered. It is found that for short-period oscillations, the Stokes layer formed by the circumferential wall movement can effectively inhibit the near-wall coherent motions and lead to skin friction reduction, while for long-period oscillations, the centrifugal instability has enough time to develop and generate new vortices, resulting in the enhancement of turbulence intensity and skin friction. 展开更多
关键词 turbulence drag reduction circumferential oscillation Taylor vortex
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基于熵权-云的数学建模竞赛创新人才评价体系研究
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作者 周涛 王倩 +1 位作者 姚依辰 杨真真 《建模与仿真》 2024年第4期4943-4952,共10页
为正确评价数学建模竞赛对大学生创新能力的影响,构建了一种新的创新能力评价指标体系,包含5个一级指标和21个二级指标,在此基础上运用熵权法对指标进行客观赋权,结合云模型和模糊综合评价理论,提出了基于熵权–云的数学建模竞赛创新人... 为正确评价数学建模竞赛对大学生创新能力的影响,构建了一种新的创新能力评价指标体系,包含5个一级指标和21个二级指标,在此基础上运用熵权法对指标进行客观赋权,结合云模型和模糊综合评价理论,提出了基于熵权–云的数学建模竞赛创新人才评价体系。以南京邮电大学数学建模竞赛情况为例,对同一批次未参与和参与数学建模竞赛并获得不同成绩的学生进行能力评价,结果表明:数学建模竞赛对于大学生的创新能力的提升有积极促进作用,同时获得奖项的学生尤其是获得国家级奖的大学生创新能力提高最为明显。 展开更多
关键词 数学建模 创新能力 云模型 熵权法 模糊综合评价法
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