Simulation of Laminar Separation Bubble Instabilities

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


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.


Direct Numerical Simulation Reverse Flow Separation Bubble Separate Shear Layer Absolute Instability 
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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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