Abstract
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 =ρ0/ρj = 4 supports sustainedside 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.
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References
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J.W. Nichols, P.J. Schmid, and J.J. Riley. Self-sustained oscillations in variable-density round jets. Journal of Fluid Mechanics, 2007 (in press).
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© 2007 Springer-Verlag Berlin Heidelberg
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Nichols, J.W., Chomaz, JM., Schmid, P.J. (2007). Secondary instability in variable-density round jets. In: Palma, J., Lopes, A.S. (eds) Advances in Turbulence XI. Springer Proceedings Physics, vol 117. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-72604-3_9
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DOI: https://doi.org/10.1007/978-3-540-72604-3_9
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-72603-6
Online ISBN: 978-3-540-72604-3
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