Flow velocimetry based on dye visualization image of tubing flow using optical flow method

In the present study, a flow visualization experiment was carried out to mimic the transmission-based X-ray imaging process. The flow visualization experiment was performed in a water tubing flow with a tube of internal diameter of 0.375 inch. A pulsating pump connected to a reservoir provides a pulsed flow with the output phase ratio of 36/64, a rate of 50 Hz, and a stroke volume of 15 CC. Red dye was used as the flow tracer. The dye was introduced through a thin tubing connected to a powered dye injector with a constant flow rate of 20 ml/min. A constant light source was placed behind the tube to provide the necessary illumination. Transmission images of the tubing flow were captured using a high-speed camera with a frame rate of 2000 FPS. Optical flow method was adopted to recover the flow field as it provides a high-resolution velocity estimation of the flow. Continuous flow patterns within 2 sec were visualized and quantified based on the transmission image of the mixing flow. The recovered flow velocity map was quantitatively compared to the Particle Image Velocimetry measurement results with the same flow condition. Although different time intervals were used to obtain the best accuracy for each technique, the overall agreement is excellent.