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Linear and weakly nonlinear aspects of free shear layer instability, roll-up, subharmonic interaction and wall influenceThe growth of the momentum thickness and the modal disturbance energies are examined to study the nature and onset of nonlinearity in a temporally growing free shear layer. A shooting technique is used to find solutions to the linearized eigenvalue problem, and pseudospectral weakly nonlinear simulations of this flow are obtained for comparison. The roll-up of a fundamental disturbance follows linear theory predictions even with a 20 percent disturbance amplitude. A weak nonlinear interaction of the disturbance creates a finite-amplitude mean shear stress which dominates the growth of the layer momentum thickness, and the disturbance growth rate changes until the fundamental disturbance dominates. The fundamental then becomes an energy source for the harmonic, resulting in an increase in the growth rate of the subharmonic over the linear prediction even when the fundamental has no energy to give. Also considered are phase relations and the wall influence.
Document ID
19860053680
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Cain, A. B.
(Notre Dame, University IN, United States)
Thompson, M. W.
(Notre Dame Univ. IN, United States)
Date Acquired
August 12, 2013
Publication Date
May 1, 1986
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
AIAA PAPER 86-1047
Accession Number
86A38418
Distribution Limits
Public
Copyright
Other

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