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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 35: Microfluidics II: Boundary conditions

CPP 35.1: Topical Talk

Donnerstag, 26. März 2009, 14:00–14:30, ZEU 160

Simulations of lubrication force experiments — •Jens Harting¹, Christian Kunert¹, and Olga I. Vinogradova² — ¹Institut für Computerphysik, Pfaffenwaldring 27, 70569 Stuttgart, Germany — ²A.N. Frumkin Institute of Physical Chemistry and Electrochemistry,Russian Academy of Sciences, 31 Leninsky Prospect, 119991 Moscow, Russia

When an object that is submerged in a liquid is approached towards a surface, the lubrication force raises. The measurement of the lubrication force gives an insight in the flow profile near objects and thus one can deduce the flow boundary condition. In particular, such a measurement can be used to study the effect of boundary slippage. Therefore many groups perform experiments, where a colloidal sphere is attached to the cantilever of an atomic force microscope (AFM) to measure the lubrication force. For the ideal situation of a perfect sphere being approached with a small, constant velocity towards a perfectly smooth wall a theoretical description is well known and a correction for boundary slip can be applied. In the case of rough boundaries and non-constant approaching velocity a theoretical description is missing. In this contribution we present lattice Boltzmann simulations of such non ideal cases and show that the known theory holds even for very rough surfaces if one applies an effective boundary.