Flow Visualization and Simultaneous Velocity and Temperature Measurements in the Wake of a Heated Cylinder

A novel optical diagnostic technique, Molecular Tagging Velocimetry and Thermometry (MTV&T), was used for qualitative flow visualization and quantitative simultaneous measurements of velocity and temperature fields in the wake of a heated cylinder. The experiment was conducted in a water channel with the heated cylinder placed horizontally in the middle of the water channel, and the flow being vertically downward to approach the heated cylinder. The temperature of the heated cylinder varied during the experiment, with the corresponding Richardson number (Ri) varying between zero (unheated) and unity. The heat transfer process around the heated cylinder changed from forced convection regime to mixed convection regime. With increasing Richardson number, significant modifications of the wake instability were revealed from both qualitative flow visualization images and quantitative simultaneous velocity and temperature fields.