A novel technique for simultaneous velocity and interface profile measurements on micro-structured surfaces

We present a novel approach which allows simultaneous measurement of the velocity field and the interface profile close to a composite liquid-gas and solid-gas interface. The proposed scheme is the method of choice for the characterization of those flows where the velocity field is highly dependent on the actual shape and position assumed by liquid-gas and liquid-solid interfaces. The new method is based on the digital processing of microscopy images of a flow seeded with fluorescent passive tracers. The relative position and the shape of both liquid-gas and liquid-solid interfaces can be determined with a resolution of few tens of nanometers. The results for the liquid-solid interfaces are also compared to an additional detection method we devised to accurately determine the absolute position of the solid walls.