采用分子动力学模拟技术,研究了纳米水滴在光滑壁面上的润湿行为规律。模拟结果表明,壁面宽度、厚度以及水分子数对接触角及汽—液界面厚度的影响不大。随着壁面作用势能的减小,接触角线性增大;当壁面作用势能为1.674 k J/mol时,接触角...采用分子动力学模拟技术,研究了纳米水滴在光滑壁面上的润湿行为规律。模拟结果表明,壁面宽度、厚度以及水分子数对接触角及汽—液界面厚度的影响不大。随着壁面作用势能的减小,接触角线性增大;当壁面作用势能为1.674 k J/mol时,接触角约为90°。随着温度的提高,汽—液界面厚度逐渐增大;疏水壁面的接触角随温度的提高而逐渐增大;对于中性壁面,温度对接触角影响不大;亲水壁面的接触角随温度的提高而逐渐减小。展开更多
Large-scale molecular dynamics simulations are used to study the dynamic processes of a nano-droplet impacting on hydrophobic surfaces at a microscopic level. Both the impact phenomena and the velocity distributions a...Large-scale molecular dynamics simulations are used to study the dynamic processes of a nano-droplet impacting on hydrophobic surfaces at a microscopic level. Both the impact phenomena and the velocity distributions are recorded and analyzed. According to the simulation results, similar phenomena are obtained to those in macro-experiments. Impact velocity affects the spread process to a greater degree than at a level of contact angle when the velocity is relatively high. The velocity distribution along the X axis during spread is wave-like, either W- or M-shaped, and the velocity at each point is oscillatory; while the edges have the highest spread velocity and there are crests in the distribution curve which shift toward the edges over time. The distribution along the Y axis is 〈- or 〉-shaped, and the segments above the middle have the lowest decrease rate in the spreading process and the highest increase rate in the retraction process.展开更多
Motion of a vertically falling nano droplet in incompressible Newtonian media with initial velocity is investigated. The instantaneous velocity and acceleration are carried out by using the variational iteration metho...Motion of a vertically falling nano droplet in incompressible Newtonian media with initial velocity is investigated. The instantaneous velocity and acceleration are carried out by using the variational iteration method(VIM) and homotopy perturbation method(HPM), which are analytical solution techniques. The obtained results are compared with Runge–Kutta method in order to verify the accuracy of the proposed methods. The results show that, the analytical solutions are in good agreement with each other and with the numerical solution. Also, the effects of sphericity(?) on the velocity and acceleration profiles of the nano droplet are explained. Moreover, the results demonstrate that the VIM-Padé and HPM-Padé are very effective in generating analytical solutions for even highly nonlinear problems.展开更多
文摘采用分子动力学模拟技术,研究了纳米水滴在光滑壁面上的润湿行为规律。模拟结果表明,壁面宽度、厚度以及水分子数对接触角及汽—液界面厚度的影响不大。随着壁面作用势能的减小,接触角线性增大;当壁面作用势能为1.674 k J/mol时,接触角约为90°。随着温度的提高,汽—液界面厚度逐渐增大;疏水壁面的接触角随温度的提高而逐渐增大;对于中性壁面,温度对接触角影响不大;亲水壁面的接触角随温度的提高而逐渐减小。
基金supported by the National Natural Science Foundation of China(Grant No.51109178)the Science and Technology Innovation Foundation ofNorthwestern Polytechnical University,China(Grant No.JC20120218)
文摘Large-scale molecular dynamics simulations are used to study the dynamic processes of a nano-droplet impacting on hydrophobic surfaces at a microscopic level. Both the impact phenomena and the velocity distributions are recorded and analyzed. According to the simulation results, similar phenomena are obtained to those in macro-experiments. Impact velocity affects the spread process to a greater degree than at a level of contact angle when the velocity is relatively high. The velocity distribution along the X axis during spread is wave-like, either W- or M-shaped, and the velocity at each point is oscillatory; while the edges have the highest spread velocity and there are crests in the distribution curve which shift toward the edges over time. The distribution along the Y axis is 〈- or 〉-shaped, and the segments above the middle have the lowest decrease rate in the spreading process and the highest increase rate in the retraction process.
文摘Motion of a vertically falling nano droplet in incompressible Newtonian media with initial velocity is investigated. The instantaneous velocity and acceleration are carried out by using the variational iteration method(VIM) and homotopy perturbation method(HPM), which are analytical solution techniques. The obtained results are compared with Runge–Kutta method in order to verify the accuracy of the proposed methods. The results show that, the analytical solutions are in good agreement with each other and with the numerical solution. Also, the effects of sphericity(?) on the velocity and acceleration profiles of the nano droplet are explained. Moreover, the results demonstrate that the VIM-Padé and HPM-Padé are very effective in generating analytical solutions for even highly nonlinear problems.
