Zhu Yingxi, Granick Steve
Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801, USA.
Phys Rev Lett. 2002 Mar 11;88(10):106102. doi: 10.1103/PhysRevLett.88.106102. Epub 2002 Feb 26.
A controversial point in fluid dynamics is to distinguish the relative importance of surface roughness and fluid-surface intermolecular interactions in determining the boundary condition. Here hydrodynamic forces were compared for flow of Newtonian fluids past surfaces of variable roughness but similar, poorly wetted, surface chemistry. The critical shear stress and shear rate to observe deviations from predictions using the no-slip boundary condition increased nearly exponentially with increasing roughness and diverged at approximately 6 nm rms roughness. We conclude that local intermolecular interactions dominated when the surface was very smooth, but roughness dominated otherwise. This quantifies the limits of both ideas.
流体动力学中一个有争议的问题是，在确定边界条件时，区分表面粗糙度和流体-表面分子间相互作用的相对重要性。在这里，我们比较了牛顿流体流过具有不同粗糙度但表面化学性质相似且润湿性差的表面时的流体动力。观察到与使用无滑移边界条件预测结果出现偏差时的临界剪切应力和剪切速率，几乎随着粗糙度的增加呈指数增长，并在均方根粗糙度约为6纳米时出现分歧。我们得出结论，当表面非常光滑时，局部分子间相互作用起主导作用，否则粗糙度起主导作用。这量化了这两种观点的局限性。
