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Conference Papers Year : 2007

Secondary instability in variable-density round jets


Side jet formation in variable-density round jets is investigated by means of direct numerical simulation (DNS) and linear stability analysis. From DNS, it is observed that a light jet with density ratio S = rho(0)/rho(j) = 4 supports sustained side jets which eject fluid from the center of the jet in a star-shaped pattern. These side jets persist over an axial distance of approximately 5 jet diameters before the jet transitions to turbulence, and do not precess around the jet. It is conjectured that this behavior can be explained by a change in the local properties of the secondary instability from convective to absolute in nature. This hypothesis is tested by examining the spatio-temporal development of the wavepacket resulting from a small impulse, taken about a non-diffusing periodic base state corresponding to the saturated primary instability.

Dates and versions

hal-01026018 , version 1 (21-07-2014)



Joseph W. Nichols, Jean-Marc Chomaz, Peter J. Schmid. Secondary instability in variable-density round jets. 11th EUROMECH European Turbulance Conference, Jun 2007, Porto, Portugal. pp.32-34, ⟨10.1007/978-3-540-72604-3_9⟩. ⟨hal-01026018⟩
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