Hyväluoma Jari, Harting Jens
Department of Physics, University of Jyväskylä, FI-40014 Jyväskylä, Finland.
Phys Rev Lett. 2008 Jun 20;100(24):246001. doi: 10.1103/PhysRevLett.100.246001. Epub 2008 Jun 16.
On hydrophobic surfaces, roughness may lead to a transition to a superhydrophobic state, where gas bubbles at the surface can have a strong impact on a detected slip. We present two-phase lattice Boltzmann simulations of a Couette flow over structured surfaces with attached gas bubbles. Even though the bubbles add slippery surfaces to the channel, they can cause negative slip to appear due to the increased roughness. The simulation method used allows the bubbles to deform due to viscous stresses. We find a decrease of the detected slip with increasing shear rate which is in contrast to some recent experimental results implicating that bubble deformation cannot account for these experiments. Possible applications of bubble surfaces in microfluidic devices are discussed.
在疏水表面，粗糙度可能导致向超疏水状态的转变，其中表面的气泡会对检测到的滑移产生强烈影响。我们给出了在带有附着气泡的结构化表面上进行库埃特流的两相格子玻尔兹曼模拟。尽管气泡给通道增加了光滑表面，但由于粗糙度增加，它们可能导致负滑移出现。所使用的模拟方法允许气泡因粘性应力而变形。我们发现，随着剪切速率的增加，检测到的滑移减小，这与最近一些实验结果相反，那些实验结果暗示气泡变形无法解释这些实验。文中讨论了气泡表面在微流体装置中的可能应用。
