Author(s)

O. Manca, S. Nardini, D. Ricci & S. Tamburrino

Abstract

A numerical transient analysis of natural convection in air in vertical divergent channels is accomplished. The channel walls are heated at uniform heat flux, the problem is two-dimensional and laminar and the full Navier-Stokes and energy equations are employed. Results in terms of average wall temperature profile, as a function of the time, wall temperature distributions for inclination angle and minimum wall spacing are presented. The simulation allows the detection of complex structures of the flow inside and outside the channel. Temperature profiles as a function of time show overshoot and undershoot. A comparison between numerical flow patterns and experimental flow visualizations are also given and a good agreement is observed. Keywords: natural convection, divergent channel, transient analysis. 1 Introduction Natural convection in channels and parallel plates received very much attention for its application in engineering as reviewed in [1, 2]. These configurations have been employed in chemical vapor deposition reactors, solar collectors, nuclear reactors, heat exchangers and thermal control of electronic systems [3,4]. Nowadays, trends in natural convection heat transfer are oriented toward either the seeking of new configurations to enhance the heat transfer parameters or the optimization of standard configurations [5, 6]. In fact, recent research efforts have been devoted to define simple geometrical modification of the channel configurations to improve its thermal performance in natural convection [5–7]. Among them divergent vertical channels with two heated principal walls are very simple ones [9–12].

Keywords

natural convection, divergent channel, transient analysis.