Shuvo Abdul Aziz, Paniagua-Guerra Luis E, Choi Juseok, Kim Seong H, Ramos-Alvarado Bladimir
Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.
Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.
Nanoscale. 2025 Jan 2;17(2):635-660. doi: 10.1039/d4nr03697b.
Nanofluidics has made significant impacts and advancements in various fields, including ultrafiltration, water desalination, biomedical applications, and energy conversion. These advancements are driven by the distinct behavior of fluids at the nanoscale, where the solid-fluid interaction characteristic lengthscale is in the same order of magnitude as the flow conduits. A key challenge in nanofluidics is understanding hydrodynamic slip, a phenomenon in which fluids flow past solid boundaries with a non-zero surface velocity, deviating from the classical no-slip boundary condition. This review consolidates experimental, computational, and theoretical efforts to elucidate the mechanisms behind hydrodynamic slip in nanoconfined flows. Key experimental methods, such as the surface force apparatus, atomic force microscopy, and micro-particle image velocimetry are evaluated alongside emerging techniques like suspended microchannel resonators, dynamic quartz crystal microbalance, and hybrid graphene/silica nanochannels, which have advanced hydrodynamic slip characterization at the nanoscale. In addition to direct slip measurement techniques, methods like sum frequency generation spectroscopy, X-ray reflectometry, and ellipsometry are discussed for their roles in probing solid-liquid interfacial interactions, shedding light on the origins of hydrodynamic slip. The review also highlights the contributions of molecular dynamics simulations, including both non-equilibrium (NEMD) and equilibrium (EMD) approaches, in modeling interfacial phenomena and slip behavior. Additionally, it explores the influence of factors such as surface wettability, shear rate, and confinement on slip, emphasizing the interaction between liquid structuring and solid-liquid interactions. Advancements made so far have uncovered more complexities in nanoconfined flows which have not been considered in the past, inviting more investigation to fully understand and control fluid behavior at the molecular level.
纳米流体学在包括超滤、海水淡化、生物医学应用和能量转换在内的各个领域都产生了重大影响并取得了进展。这些进展是由纳米尺度下流体的独特行为驱动的，在该尺度下，固液相互作用特征长度尺度与流动管道处于同一数量级。纳米流体学中的一个关键挑战是理解流体动力滑移，即流体以非零表面速度流过固体边界的现象，这与经典的无滑移边界条件不同。本综述整合了实验、计算和理论方面的研究成果，以阐明纳米受限流动中流体动力滑移背后的机制。评估了诸如表面力仪、原子力显微镜和微粒图像测速仪等关键实验方法，以及诸如悬浮微通道谐振器、动态石英晶体微天平、石墨烯/二氧化硅混合纳米通道等新兴技术，这些技术推动了纳米尺度下流体动力滑移的表征。除了直接滑移测量技术外，还讨论了和频产生光谱、X射线反射仪和椭偏仪等方法在探测固液界面相互作用、揭示流体动力滑移起源方面的作用。该综述还强调了分子动力学模拟的贡献，包括非平衡（NEMD）和平衡（EMD）方法，用于模拟界面现象和滑移行为。此外，它还探讨了表面润湿性、剪切速率和限制等因素对滑移的影响，强调了液体结构与固液相互作用之间的相互作用。迄今为止取得的进展揭示了纳米受限流动中更多过去未被考虑的复杂性，这促使人们进行更多研究，以在分子水平上全面理解和控制流体行为。
