University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Stability analysis of separated flows subject to control by zero-net-mass-flux jet

Marxen, O, Kotapati, RB, Mittal, R and Zaki, T (2015) Stability analysis of separated flows subject to control by zero-net-mass-flux jet Physics of Fluids, 27 (2).

Full text not available from this repository.


© 2015 AIP Publishing LLC.The control of flow around a canonical airfoil-like geometry with laminar separation bubble is analyzed using linear stability theory. The theoretical predictions are compared to data from Navier-Stokes simulations [Kotapati et al., "Nonlinear dynamics and synthetic-jet-based control of a canonical separated flow," J. Fluid Mech. 654, 65-97 (2010)], in which the flow was controlled through a zero-net-mass-flux actuator. Very good agreement between the two approaches is found for a range of frequencies from low to high relative to the most dominant frequency for convective instability. The uncontrolled case exhibits periodic vortex shedding from the separation bubble due to an absolute instability. Linear modes with intermediate frequencies are found to exhibit strongest convective amplification, and forcing at these frequencies is most effective in order to reduce the size and extent of the separation bubble. The corresponding physical mechanism relies on a Kelvin-Helmholtz instability of the separated shear layer in conjunction with the non-linear effect of the mean flow deformation. For low frequencies, the front part of the bubble still diminishes due to the interaction of a vortex that starts from the actuator with the wall. This vortex transiently amplifies downstream due to the Orr mechanism. Actuation at high frequencies leads to visible, amplified instability waves in the shear layer, but is not effective in reducing the size of the bubble.

Item Type: Article
Divisions : Surrey research (other units)
Authors :
Kotapati, RB
Mittal, R
Zaki, T
Date : 17 February 2015
DOI : 10.1063/1.4907362
Depositing User : Symplectic Elements
Date Deposited : 17 May 2017 13:35
Last Modified : 25 Jan 2020 00:09

Actions (login required)

View Item View Item


Downloads per month over past year

Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800