Ballooning in Spiders using Multiple Silk Threads
Ballooning in Spiders using Multiple Silk Threads
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DOI：
10.1103/physreve.105.034401
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发表时间：
2021-12
期刊：
影响因子：
--
通讯作者：
C. Habchi;M. Jawed
中科院分区：
文献类型：
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作者：
C. Habchi;M. Jawed
本文采用离散弹性杆法，对蜘蛛体内多根丝线的气胀运动进行了三维数值模拟。蜘蛛的膨胀被假设是由于蜘蛛丝的负电荷和地球大气层中的正电势场的存在而引起的。这里提出的数值模型首先验证实验数据从公开文献。在此之后，两种情况下进行了检查，在第一个假设，电荷是均匀分布的沿着线程，而在第二个，电荷位于线程的尖端。结果表明，归一化的终端气球速度，即，蜘蛛在达到稳定状态后膨胀的速度随着归一化升力线性减小，特别是对于尖端定位的电荷情况。对于均匀电荷的情况下，这个速度表现出稍微弱的依赖于归一化升力。此外，它示出在这两种情况下，归一化终端气胀速度没有依赖于归一化的弹性弯曲刚度的线程和归一化的粘性力。最后，多螺纹弯曲过程显示了三维锥形片材。在这里，我们表明，这种行为是由库仑排斥力，由于线程的电荷，导致分散的线程分开，从而避免纠缠。
In this paper, three-dimensional numerical simulations of ballooning in spiders using multiple silk threads are performed using the discrete elastic rods method. The ballooning of spiders is hypothesized to be caused by the presence of the negative electric charge of the spider silk threads and the positive electric potential field in the Earth's atmosphere. The numerical model presented here is first validated against experimental data from the open literature. After which, two cases are examined, in the first it is assumed that the electric charge is uniformly distributed along the threads while in the second, the electric charge is located at the thread tip. It is shown that the normalized terminal ballooning velocity, i.e., the velocity at which the spiders balloon after they reach steady-state, decrease linearly with the normalized lift force, especially for the tip located charge case. For the uniform electric charge case, this velocity shows a slightly weaker dependence on the normalized lift force. Moreover, it is shown in both cases that the normalized terminal ballooning velocity has no dependence on the normalized elastic bending stiffness of the threads and on the normalized viscous forces. Finally, the multithread bending process shows a three-dimensional conical sheet. Here we show that this behavior is caused by the Coulomb repelling forces owing to the threads electric charge which leads to dispersing the threads apart and thus avoid entanglement.