Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 46: P11: Wetting, Micro and Nano Fluidics

CPP 46.6: Poster

Wednesday, March 18, 2015, 10:00–13:00, Poster A

Quantification of spontaneous imbibition processes in nano-porous systems — •Christian Thome and Heiko Rieger — Universität des Saarlandes, Saarbrücken, Germany

The study of spontaneous imbibition processes in micro- and nano-pores is important for various applications like oil recovery, water flow through soil or drug design. In porous media with elongated pores one can observe a dynamical broadening of the imbibition front which is caused by the temporal arrest of some menisci. This effect has also been shown by microfluidic studies in y-shaped junctions. Here the arrest time of the meniscus in the bigger channel is proportional to the feeding channel length. In contrast to microfluidic channels nanofluidic devices have a high surface-to-volume ratio. As an example we consider a system where a piece of nano-porous vycor glass is in contact with a water reservoir. Density fluctuations over intermolecular distances can be important in this system. For this reason we investigate the flow beavior of the imbition process of water in nano-porous vycor glass with molecular dynamics simulations using a simple Lennard Jones model fluid. The imbibition speed of the meniscus and the speed of the fluid layer in direct contact to the wall atoms is estimated as a function of the wall/fluid-particle-interaction-strength. Futhermore we consider a nano-pore-junction connecting 3 nano-pores of different radii. After filling the feeding channel, the liquid penetrates the smaller of the two outgoing channels and arrests in the bigger one. The arrest time of the meniscus in the bigger tube is determined as a function of the feeding channel length for different junction geometries.