Hydrodynamic Enhancement of the Diffusion Rate in the Region between Two Fluctuating Membranes in Close Opposition: A Theoretical and Computational Study

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• 作者：Martina Pannuzzo ; Antonio Grassi ; Antonio Raudino
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：July 24, 2014
• 年：2014
• 卷：118
• 期：29
• 页码：8662-8672
• 全文大小：528K
• ISSN：1520-5207

文摘

Periodic variation of the distance between two weakly adhering bodies gives rise to a huge tangential motions of the sandwiched solvent layer (squeezing flow). Oscillations either can be induced by an external applied field or can spontaneously arise from the coupling with the solvent heat bath. First we calculated by the Navier鈥揝tokes equation the components of the fluid velocity near two oscillating juxtaposed plates. Then we evaluated the influence of plate oscillations on the transport properties of a trace diffusant dissolved at t = 0 in the outer medium for both deterministic and stochastic excitations. By employing both analytical (Fokker鈥揚lanck) and coarse-grained molecular dynamics (MD) simulations, we proved that the entry and migration rates of the diffusant sharply increases with the oscillation amplitudes. Enhancement was related to relevant parameters like oscillation frequency, fluid layer thickness, fluid viscosity, and temperature. An extension to the case of oscillating multistacked lamellae has been also made. Theoretical and MD results suggest a significant enhancement of the diffusant flux even in the worse situation of thermally excited small amplitude fluctuations. Excitation arising from other sources (e.g., microwave or ultrasound irradiation of solid鈥揻luid layered systems) could have a dramatic effect on the transport phenomena. Possible implications to relevant biological problems have been discussed.