Agrawal Adyant, Gravelle Simon, Kamal Catherine, Botto Lorenzo
School of Engineering and Material Science, Queen Mary University of London, London, UK.
Process and Energy Department, 3ME Faculty of Mechanical, Maritime and Materials Engineering, TU Delft, Delft, The Netherlands.
Soft Matter. 2022 May 25;18(20):3967-3980. doi: 10.1039/d1sm01743h.
Combining molecular dynamics (MD) and continuum simulations, we study the dynamics of propagation of a peeling front in a system composed of multilayered graphene nanosheets completely immersed in water. Peeling is induced by lifting one of the nanosheet edges with an assigned pulling velocity normal to the flat substrate. Using MD, we compute the pulling force as a function of the pulling velocity, and quantify the viscous resistance to the advancement of the peeling front. We compare the MD results to a 1D continuum model of a sheet loaded with modelled hydrodynamic loads. Our results show that the viscous dependence of the force on the velocity is negligible below a threshold velocity. Above this threshold, the hydrodynamics is mainly controlled by the viscous resistance associated to the flow near the crack opening, while lubrication forces are negligible owing to the large hydrodynamic slip at the liquid-solid boundary. Two dissipative mechanisms are identified: a drag resistance to the upward motion of the edge, and a resistance to the gap opening associated to the curvature of the flow streamlines near the entrance. Surprisingly, the shape of the sheet was found to be approximately independent of the pulling velocity even for the largest velocities considered.
结合分子动力学（MD）和连续介质模拟，我们研究了完全浸没在水中的多层石墨烯纳米片系统中剥离前沿的传播动力学。通过以垂直于平坦基底的指定拉动速度提升纳米片边缘之一来引发剥离。使用分子动力学，我们计算了作为拉动速度函数的拉力，并量化了对剥离前沿推进的粘性阻力。我们将分子动力学结果与加载了模拟流体动力载荷的薄片的一维连续介质模型进行了比较。我们的结果表明，在阈值速度以下，力对速度的粘性依赖性可以忽略不计。高于此阈值，流体动力学主要由与裂纹开口附近流动相关的粘性阻力控制，而由于液固边界处的大流体动力滑移，润滑力可以忽略不计。确定了两种耗散机制：对边缘向上运动的阻力，以及与入口附近流线曲率相关的间隙开口阻力。令人惊讶的是，即使对于所考虑的最大速度，薄片的形状也被发现大致与拉动速度无关。
