A numerical and experimental analysis on the natural convective heat transfer of a small heating strip located on the floor of a square cavity

In this paper it is analyzed the influence of the position of a small heating source placed on the bottom wall of a square cavity filled by air (Pr = 0.71). We studied a strip of a determined dimensionless length of ε = 1/5 that is located at two different dimensionless distances from the left side of the cavity: the first one is δ = 0.4 (asymmetrical position) and the second one is δ = 0.5 (symmetrical position). The experimental analysis was carried out through an holographic interferometry and through a 2D PIV system. The holographic interferometry was used by the real-time technique and by the double-exposure technique. In the first case we analyzed the presence of the plume oscillations and we determined the achievement of the steady state; in the second case we concentrated on the air temperature distributions, consequently we measured the Nusselt numbers on the heated strip at different Rayleigh numbers. The experimental study also included an analysis through a 2D Particle Image Velocimetry (PIV), that allowed us to measure the velocity fields and the dynamic structures generated by the heat transfer at the same Rayleigh numbers. Measured quantities were compared with the numerical results which were obtained through the finite volume code Fluent 6.2.16.