Full 3D-3C velocity measurement inside a liquid immersion droplet

Abstract

We describe a tomographic PIV system for the measurement of the internal flow in a droplet over a stagnant and a moving surface. The flow condition is representative of the flow in an immersion droplet applied in a liquid immersion lithography machine. We quantify the accuracy and reliability of the measurements and compare the shape of the reconstructed measurement volume to shape measurements by means of shadowgraphy. First results indicate the internal flow pattern near the receding contact line, showing a small recirculation region.

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

“…4. Viewing angles of 20°were reported by Kim et al (2011), who used a self-made microscope and applied four cameras to investigate the flow inside a droplet on a moving surface tomographically. The measurement volume was 2.5 9 2.1 9 0.4 mm 3 .…”

Tomographic PIV measurement of internal complex flow of an evaporating droplet with non-uniformly receding contact lines

“…Furthermore, this method is able to reconstruct the liquid-air interface by an average-reconstructed intensity distribution. (15) For multi-camera measurement technique, an inverted (i.e., upsidedown) custom-made microscope (Carl Zeiss Neolumar S1.5×) is equipped with optical filters set and with four dual-frame CCD cameras (LaVision Imager intense, 1376 × 1040 pixels, 12-bit dynamic range) is used for imaging, as shown in figure 1.…”

“…It is still challenging work to measure a flow field directly through the liquid-gas interface. In other ways, to minimize the optical distortion through the media, an inverted measurement system is commonly used (14,15) . Pradhan and Panigrahi (14) performed the flow field measurement inside the evaporating droplet by using scanning confocal microscope.…”

“…Pradhan and Panigrahi (14) performed the flow field measurement inside the evaporating droplet by using scanning confocal microscope. Kim et al (15) obtained the full three-dimensional three velocity vector components (3D-3C velocity vectors) near the liquid-air interface by tomographic PIV with an inverted measurement system. Furthermore, they obtained the three-dimensional dewetting corner structure by using a tomographic reconstruction technique.…”

“…Furthermore, they obtained the three-dimensional dewetting corner structure by using a tomographic reconstruction technique. (15) They showed that tomographic PIV is capable of measuring the complex micro-scale flow patterns where the liquid-air interface exists. In this paper, we investigate a flow pattern of evaporating droplet where the contact line nonuniformly recedes in time and space.…”