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中国物理学会期刊

温差条件下包含手征活性粒子的封闭圆环的输运

CSTR: 32037.14.aps.72.20221772

Transport of closed ring containing chiral active particles under transversal temperature difference

CSTR: 32037.14.aps.72.20221772
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  • 在温差条件下, 由于二维周期通道的横向温度差引发的上下不对称和活性粒子的手征性质使得活性粒子在纵向发生定向运动, 继而驱动包裹粒子的封闭圆环定向输运. 圆环的运动方向由粒子的手征性决定. 研究表明, 圆环的运动速度是活性粒子的角速度、下壁温度及温度差的峰值函数. 圆环包含一个手征活性粒子与包含多个手征活性粒子的定向运动行为具有较大差异. 特别是, 圆环半径对两种情况下圆环的运动行为差异影响较大. 当封闭圆环只包含一个粒子且粒子做圆周运动的轨迹半径较大(小)时, 粒子与圆环的相互作用对圆环定向运动起促进(抑制)作用, 圆环速度随圆环半径增大而减小(增大); 当封闭圆环包含多个粒子时, 粒子间的相互作用对圆环定向运动起抑制作用, 圆环半径越大, 粒子间相互作用越弱, 圆环速度越大. 本文的研究结果为在微尺度上活性粒子流的操控提供了新的可能性.

     

    Active matter is a new and challenging field of physics. Chiral active particle experiences a constant torque and performs circular motion due to the self-propulsion force not aligning with the propulsion direction. Recently, most of studies of the active particle systems focused on constant temperature, but did not take into consideration the constraints by the barriers. In our work, the rectification of a ring containing chiral active particles with transversal temperature difference is numerically investigated in a two-dimensional periodic channel. It is found that the ring powered by chiral active particles can be rectified by the transversal temperature difference and the direction of the transport is determined by the chirality of active particles. The average velocity is a peaked function of angular velocity, the temperature of the lower wall or temperature difference. The transport behaviors of the ring containing one chiral active particle is qualitatively different from those of the ring containing several particles. Especially, the ring radius can strongly affect the transport behaviors. For the ring containing one chiral active particle, the interaction between the particle and the ring facilitates the rectification of the ring when the circular trajectory radius of the chiral particle is large. The average velocity decreases with the increase of the ring radius because the propelling force to the ring by the particle is small. When the circular trajectory radius is small, the interaction between the particle and the ring suppresses the transport. The speed increases as the ring radius increases because the directional transport comes from the difference in temperature between the upper wall and the lower wall. For the ring containing several particles, the interaction between particles reduces the rectification of the ring. The average velocity increases with the increase of the ring radius due to the interaction between particles decreasing. Remarkably, the velocity of the ring decreases as the particle number increases when the ring radius is small, but is a peaked function when the ring radius is not small. Our results offer new possibilities for manipulating an active particle flow on a microscale, and can be applied practically to propelling carriers and motors by a bath of bacteria or artificial microswimmers, such as hybrid micro-device engineering, drug delivery, micro-fluidics, and lab-on-chip technology.

     

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