Fundamental mode of freely decaying laminar swirling flows

François Beaubert (1) , Halldor Pálsson (2) , Sylvain Lalot (1) , Isabelle Choquet (3) , Hadrien Bauduin (1)

1 LAMIH - Laboratoire d'Automatique, de Mécanique et d'Informatique industrielles et Humaines - UMR 8201
2 University of Iceland [Reykjavik]
3 Univ West, Dept Engn Sci, SE-46186 Trollhattan, Sweden

A detailed study of a swirling flow in a tube is presented in the first part of the paper. A simplified analytical solution of the governing equations indicates specific modes of the tangential velocity and that the decay of the swirl effect is exponential. The problem is then solved in three dimensions using computational fluid dynamics (CFD) and a comparison with analytical expressions shows that the CFD code is reliable in terms of accuracy. The CFD results confirm that a fundamental swirling mode is reached within a short distance from the inlet. The torque swirl number is introduced to physically estimate the intensity of the swirl. A companion value is given: it is the average deviation.

Mots clés: "Laminar"; "Decay"; "Swirl"; "Analytical"; "Boundary condition"; "OpenFOAM"

Domaines: Mécanique [physics.med-ph]

François Beaubert, Halldor Pálsson, Sylvain Lalot, Isabelle Choquet, Hadrien Bauduin. Fundamental mode of freely decaying laminar swirling flows. Applied Mathematical Modelling, 2016, 40 (13-14), pp.6218-6233. ⟨10.1016/j.apm.2016.02.002⟩. ⟨hal-03443124⟩