A technique is described to measure the instantaneous 2D temperature distribution in the wake of a heated cylinder using `laser-induced fluorescence'. Rhodamine B, a fluorescent dye, is used as a temperature indicator. The relation between fluorescence intensity and temperature is determined by means of calibration experiments in the temperature range of 20–35¿°C with an accuracy of ±0.1¿°C. The temperature distribution behind the heated cylinder is well visible and can be measured with a high spatial resolution. Corrections for variation in laser energy and intensity distribution in the laser sheet have to be made to further improve the accuracy of the measuring method.
Seuntiens, H. J., Kieft, R. N., Rindt, C. C. M., & Steenhoven, van, A. A. (2001). 2D temperature measurements in the wake of a heated cylinder using LIF. Experiments in Fluids, 31(5), 588-595. https://doi.org/10.1007/s003480100338