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中国物理学会期刊

限域通道内溶液的电渗流滑移减阻机制

CSTR: 32037.14.aps.74.20250440

Electroosmotic slip reduction mechanism of solutions in domain-limited channels

CSTR: 32037.14.aps.74.20250440
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  • 电渗流通过改变流固界面的双电层效应, 使流体在通道内产生高剪切率从而驱动界面处产生大的滑移速度. 本文采用分子动力学模拟构建电渗流纳米通道模型, 研究了石墨烯带电壁面纳米通道内流体流动特性与壁面滑移减阻特性. 结果表明, 电渗流改变了双电层结构增加其扩散层的可移动性; 同时在电场作用下扩散层的离子定向迁移, 通过黏性作用带动整体流动, 增大了流体的流动性能. 引入离子后, Na+在壁面处吸附削弱流体与壁面之间的吸附力, 从而提升流体在限域空间的驱动力, 增大离子溶液滑移长度和流速. 最终提出了一种通过调控石墨烯非对称壁面电荷实现通道内溶液超快运输的方法, 成功地实现了石墨烯通道内溶液电渗流的滑移减阻效果. 为纳米限域空间内微流体的快速节能输运提供了理论依据.

     

    Electroosmosis drives a large slip velocity at the interface by altering the electrokinetic double layer effect at the fluid-solid interface, thereby generating high shear rates within the channel. In this paper, molecular dynamics simulations are used to construct an electroosmotic flow nanochannel model, and the fluid flow characteristics and wall slip reduction properties within graphene charged-wall nanochannels are investigated. The results show that the electroosmotic flow changes the structure of the bilayer to increase the mobility of its diffusion layer, and at the same time, the ions in the diffusion layer under the action of the applied electric field undergo directional migration and drive the overall fluid flow through the viscous effect, which enhances the mobility performance. After the introduction of ions, Na+ is adsorbed at the wall surface, which weakens the adsorption force between the fluid and the wall surface and enhances the driving force of the fluid in the confined domain space, thus increasing the slip length and flow rate. Finally, by modulating the charge size on the upper and lower wall surfaces, asymmetric channel wall charges are formed. The electric field gradient superimposed on the applied electric field further enhances the driving force of ions, changes the distribution of the of Na+ adsorption layer and the migration behavior of Cl, thereby increasing the transport of the solution in the channel. Therefore, in this paper, a method is proposed to realize the ultrafast transport of solution in the channel by modulating the asymmetric wall charge of graphene, successfully achieving the slip reduction effect of the electroosmotic flow of solution in the graphene channel. A theoretical basis is laid for the fast and energy-saving transportation of microfluidics in the nano-limited space.

     

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