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Science and Technology of Nuclear Installations
Volume 2008, Article ID 895695, 10 pages
Research Article

Numerical Analysis of General Trends in Single-Phase Natural Circulation in a 2D-Annular Loop

1INSSET/LETEM, Université de Picardie Jules Verne, 48 rue Raspail, BP 422, 02109 Saint-Quentin, France
2Dipartimento di Ingegneria Industriale e Meccanica, Università di Catania, Viale A. Doria 6, 95125 Catania, Italy

Received 16 May 2007; Accepted 23 November 2007

Academic Editor: John Cleveland

Copyright © 2008 Gilles Desrayaud and Alberto Fichera. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this paper is to address fluid flow behavior of natural circulation in a 2D-annular loop filled with water. A two-dimensional, numerical analysis of natural convection in a 2D-annular closed-loop thermosyphon has been performed for various radius ratios from 1.2 to 2.0, the loop being heated at a constant flux over the bottom half and cooled at a constant temperature over the top half. It has been numerically shown that natural convection in a 2D-annular closed-loop thermosyphon is capable of showing pseudoconductive regime at pitchfork bifurcation, stationary convective regimes without and with recirculating regions occurring at the entrance of the exchangers, oscillatory convection at Hopf bifurcation and Lorenz-like chaotic flow. The complexity of the dynamic properties experimentally encountered in toroidal or rectangular loops is thus also found here.