To measure the parameters of fiber and to visualize the reshaping process of fiber in air tunnel, an experimental approach is developed in the present work. The tunnel is designed with gradient flow velocity, and the fiber reshaping images as well as the fiber length value are obtained experimentally. An analytical expression of velocity distribution in the tunnel is theoretically derived and the simulated results are obtained. Automatic fiber reshaping including stretch and rotation is verified using the dynamical equation and the multi-spherical chain model. It is shown that pull force by air flow makes a chain of balls become straight and Stokes moment makes the ball chain rotate. Finally, reshaping criterion related with flow velocity is formulated.

中文翻译：

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光纤在空气隧道中以速度梯度运动的可视化*

为了测量纤维的参数并可视化空气通道中纤维的重塑过程，本工作开发了一种实验方法。设计了具有梯度流速的隧道，并通过实验获得了纤维整形图像以及纤维长度值。理论上推导了隧道内速度分布的解析表达式，并得到了模拟结果。使用动力学方程和多球链模型验证了包括拉伸和旋转在内的自动纤维重塑。结果表明，气流产生的拉力使滚珠链变得笔直，而斯托克斯矩使滚珠链旋转。最后，制定了与流速有关的重塑准则。