Particle Image Thermometry for Natural Convection Flows

Abstract

Particle Image Thermometry (PIT) is a technique by which temperature fields can be obtained non-invasively using thermochromic liquid crystals (TLCs) through image processing of experimental true-colour photographs. This is done using a calibration curve (hue versus temperature). With the calibration data, every pixel of the colour photograph is transformed to a temperature value, and thus accurate experimental temperature maps are obtained. Using this technique, examples of steady and unsteady natural convection are presented, which include steady magnetic convection of paramagnetic fluids in a cubic enclosure heated and cooled from opposite walls, and unsteady convective flows in a reservoir model cooled from above (night-time cooling). The instantaneous measurement of temperature fields is very useful for understanding flow characteristics in situations where conventional flow visualisation is not sufficient. This method also provides additional quantitative information for comparisons with numerical modelling