Capillary imbibition of water plays a significant role in various applications at both the macroscopic and microscopic scales. However, it is still unclear whether capillary imbibition could be manipulated by the geometry structure of the nanotubes. In this paper, we adjust the concentric tube length difference ∆L of the double-walled nanotubes (DWNTs) to manipulate the capillary imbibition by molecular dynamics simulations. Three configurations are considered, i.e. ∆L = 0 (the common DWNT structure, labeled as configuration I), ∆L < 0 (configuration II, the inner tube is shorter than the outer tube), and ∆L > 0 (configuration III, the inner tube is longer than the outer tube). By comparing with the single-walled nanotube, it is found that the imbibition velocities of the water molecules in the DWNT are weakened 9.1% in configuration I and enhanced 30%–46.5% in configuration II and 10% in configuration III. By analyzing the microscopic structure of the water molecules, it is found that the imbibition velocity adjustment originates from the potential energy difference of the water molecules in the water reservoir and at the entrance of the nanotube at the nanotube cylindrical pore. An exponential relation between the imbibition velocity v _L and the potential energy difference ΔE is obtained as . Furthermore, it is found that imbibition velocity is independent from the radius differences in all three configurations. Our results suggest a possible way to manipulate the capillary imbibition behavior and it has significant implications for water treatment, nano-switches, catalysis engines and biological sensors.

水的毛细管吸水在宏观和微观尺度的各种应用中都发挥着重要作用。然而，尚不清楚毛细管吸吸是否可以通过纳米管的几何结构来操纵。在本文中，我们通过分子动力学模拟调整双壁纳米管 (DWNTs)的同心管长度差 Δ L以操纵毛细管渗吸。考虑了三种配置，即 ∆ L = 0（常见的 DWNT 结构，标记为配置 I），∆ L < 0（配置 II，内管短于外管）和 ∆ L> 0（配置三，内管比外管长）。通过与单壁纳米管的比较，发现 DWNT 中水分子的吸入速度在配置 I 中减弱了 9.1%，在配置 II 中增强了 30%–46.5%，在配置 III 中增强了 10%。通过对水分子微观结构的分析发现，渗吸速度的调节源于水库中水分子与纳米管圆柱孔处纳米管入口处的水分子势能差。吸入速度v _L与势能差 Δ E之间的指数关系为 . 此外，发现在所有三种配置中，吸入速度与半径差异无关。我们的研究结果提出了一种可能的方法来操纵毛细管吸收行为，它对水处理、纳米开关、催化引擎和生物传感器具有重要意义。