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Simulation of Laminar Separation Bubble Instabilities

  • M. Alam
  • N. D. Sandham
Conference paper
Part of the ERCOFTAC Series book series (ERCO, volume 5)

Abstract

Direct numerical simulations of the three-dimensional (3-D) time-dependent incompressible Navier-Stokes equations are performed to investigate the growth and stability of separation bubbles, generated by suction of fluid through the upper boundary of the simulation. Temporal stability of a family of matching analytic profiles for steady laminar separation bubbles is investigated by solving the Orr-Sommerfeld equation. A wave packet analysis of the growing modes suggests that absolute instability can exist in the strong reverse flow region of a laminar separation bubble. A comparative study is made of three cases. In the first a high suction strength is used to generate a self-excited irregular vortex shedding. The second and third cases use a lower suction strength and compare two and three-dimensional forced bubbles. Small scale structures in the 3-D forced bubble were found to have little effect on the time-averaged bubble length.

Keywords

Direct Numerical Simulation Reverse Flow Separation Bubble Separate Shear Layer Absolute Instability 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 1997

Authors and Affiliations

  • M. Alam
    • 1
  • N. D. Sandham
    • 1
  1. 1.Department of EngineeringQueen Mary and Westfield CollegeLondonUK

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