Recent advances in measurement techniques using the photo-thermal effect have drawn more and more attention to the application in various fields. Especially, laser measurements are becoming increasingly important for the thermal design of electronic devices because these measurements can be applied to non-invasive and non-destructive measurement [1, 2]. We focus on the transient lens effect, which is a well-known photo-thermal phenomenon. As this effect is caused by the change of thermal properties or other physical properties, the measurements using this effect have the possibility to measure various materials information. This phenomenon has the optical property of a concave lens since the refractive index distribution on the optical axis is formed when the liquid is irradiated. One reason for the refractive index distribution in the liquid is the temperature distribution in the liquid when it is irradiated. In this research we investigate the interaction between the intensity distribution of the probe beam and temperature distribution on the Transient lens effect, in order to develop fluidic optical devices and non-invasive, non-destructive measurement.
This paper described the effect of aspect ratio on mixed convection in horizontal rectangular duct with heated and cooled side walls numerically and experimentally. In the numerical analysis, fluid flow and temperature distributions for Ri = 1.61, Pr = 6.99, Re = 100 and aspect ratio, Ar = 0.2 ˜ 10, were obtained by solving non-dimensional governing equations by SIMPLE procedure. QUICK scheme was applied to convection term of these equations. In the experimental analysis, flow behavior for Ar = 0.5 ˜ 2 was visualized by dye-injection method. Numerical results show that the swirl flow was generated along the flow direction, and its pitch length was influenced with Ar. The pitch length was the shortest in Ar = 0.5 ~ 1, and this tendency was the same in numerical results and experimental results. The heat transfer behavior was also discussed corresponding to the flow, and the heat transfer ratio was highest at Ar = 1 in 0.2 < Ar < 10.