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Onset of mixing layer instability in flow past a plate
Author(s) -
Mittal Sanjay
Publication year - 2008
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.1862
Subject(s) - wake , instability , mechanics , boundary layer , perturbation (astronomy) , vortex , mean flow , incompressible flow , physics , vortex shedding , flow (mathematics) , convection , mathematics , convective instability , classical mechanics , geometry , turbulence , reynolds number , quantum mechanics
A global stability analysis of the flow past a flat plate, normal to the flow, is carried out to determine the critical Re for the onset of convective instability of the mixing‐layer‐type modes. To suppress the primary wake mode, which leads to von Karman vortex shedding, flow past one half of the plate is studied and symmetry conditions are enforced along the wake centerline. The linearized perturbation equations for an incompressible flow are written in a moving frame of reference that travels with the perturbation and solved using a stabilized finite element method. The critical Re for the onset of convective instability is found to be 22, approximately, for H =5. Here, H is the distance of the lateral boundary from the plate centerline. Computations have also been carried out for H =10 and 20. The critical Re decreases with increase in H . Excellent agreement is observed between the results from global stability analysis and direct time integration of linearized disturbance equations. The results from the global analysis are compared with earlier reported results from local analysis of a Gaussian wake profile. Copyright © 2008 John Wiley & Sons, Ltd.