Near-wall velocities at topologically structured surfaces

Recent research has shown that hydrodynamic slippage exists due to the change in properties of the surface, such as the wettability and roughness of coatings. This hydrodynamic slippage is quantified by the so-called slip length and can be deter-mined from near-wall velocites (or slip velocities). One technique that is capable of measuring near-wall flow velocities is evanescent wave velocimetry. This technique uses an exponentially decaying evanescent wave for the illumination of fluorescent colloidal tracers. Using this technique it is possible to determine two velocity compo-nents parallel to the wall averaged over the first few hundred nanometer next to wall along the optical axis.

Project description

The primary goal of this project is to determine slip lengths by measuring flow velocities very close to the surface (ranging from 100 to 500nm) using total internal reflection fluorescence microscopy (TIRFM) with a Statistical Particle Tracking Velocimetry (SPTV) and/or Particle Image Velocimetry technique. This in order to get more insight into the slip lengths and the relation with the dimensions of the struc-tured surface. Furthermore, the experimental results can be compared with CFD simulations.
This project can be used to finish your M.Sc.-study “Solid & Fluid Mechanics”, “SPET”, or “MSP”.

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