Three component velocity extraction method using TR-PIV in a microtube

Measurement of three-component (3C) velocity field in the microfluidic devices with the conventional techniques and conventional micro-PIV (Particle Image Velocimetry) is still difficult due to the limited optical access to the microscale flow fields. Since Santiago \textit{et al} (1998), micro-PIV flow velocity measurements have remained mainly limited to the 2C velocity vector field realizations. In this study, third component of the velocity i.e. out-of-plane velocity extraction from two-dimensional time resolved (TR) micro-PIV images is proposed. The method is based on PIV and performs cross-correlation (CC) peak height tracking inside the small ensembles of the TR-PIV flow images. This concept was verified basically by the simulation employing synthetic micro TR-PIV images. It was also demonstrated by an experiment erformed on a microscale fluid flow inside a 100$\mu $m diameter inclined micro tube. Despite the inevitable background noise which effects the measurement negatively, extracted steady-state depthwise velocity profile was in agreement with the analytical result.