Ψ-PIV: A novel framework to study unsteady microfluidic flows

In micro-PIV, reaching the optimum image density has always been difficult due to high displacement gradient, coagulation of particles at the inlet and due to particles adhering to the surface to name a few. The most widely used method is to take ensemble correlation average of multiple PIV images to extract the velocity field. However, this leads to low temporal resolution. Hence, a method with high temporal resolution is pivotal to study unsteady laminar flow in microfluidic application. This work aims at developing a new PIV algorithm which reduces the effective seeding density and at the same time yield similar if not higher SNR compared to conventional PIV. We call this algorithm Ψ-PIV. This method is suitable for steady and unsteady laminar flows which are generally found in microfluidic applications. The reliability and the precision of the new method as a function of particle image pairs is investigated by synthetic image analysis. The main advantage of Ψ-PIV is its ability to achieve higher temporal resolution from the typical micro-PIV raw images. The experimental investigation for the flow around a 2D cylinder in a Hele-Shaw cell showed that the Ψ-PIV results in a reduction by approximately a factor of 25 in the number of frames required compared to conventional PIV