Articles techniques et présentations

Stationary flow configurations in curved pipes constitute an important subject from both the theoretical and the practical point of view. A typical application concerns the calculation of secondary flow effects on the thermal efficiency of heat exchangers. Motivated by a similar problem, this paper investigates the flow patterns in a helical duct of non trivial cross section. The considered regime is essentially laminar. A particular attention is devoted to the investigation of Dean structures, i.e., the recirculation cells arising in the secondary flow. The effect of duct torsion is put in evidence by an explicit comparison with a toroidal geometry of identical cross-section.