Effect of nonlinearities on the frequency response of a round jet
File(s)
Accepted version
Author(s)
Qadri, UA
Schmid, PJ
Type
Journal Article
Abstract
We investigate the effect of nonlinearities on the frequency response of a round, incompressible jet. Experiments show that axisymmetric structures dominate the response of forced and unforced jets. In contrast, linear stability and frequency response analyses predict the asymmetric mode (m=1) to be locally more unstable and globally more amplified than the axisymmetric mode (m=0). We perform a weakly nonlinear expansion of the response of the flow to harmonic forcing and derive an asymptotic expression for the sum of this divergent series beyond its limit of validity. This expression compares reasonably well with the nonlinear gain up to forcing amplitudes an order of magnitude greater than the limit of validity of the weakly nonlinear expansion. For equal forcing amplitudes, the asymmetric mode dominates over the axisymmetric mode. This suggests that the projection of environmental forcing onto the individual azimuthal modes plays an important role in the preferred dynamics of round jets.
Date Issued
2017-04-25
Date Acceptance
2017-03-30
Citation
Physical Review Fluids, 2017, 2
ISSN
2469-990X
Publisher
American Physical Society
Journal / Book Title
Physical Review Fluids
Volume
2
Copyright Statement
© 2017 American Physical Society
Subjects
Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
Physics
STABILITY
CYLINDER
FLOWS
Publication Status
Published
Article Number
043902