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Physics of Fluids / Volume 24 / Issue 2 / ARTICLES / Instability and Transition

Phys. Fluids 24, 024101 (2012); http://dx.doi.org/10.1063/1.3680864 (21 pages)

Study of instabilities and transitions for a family of quasi-two-dimensional magnetohydrodynamic flows based on a parametrical model

S. Smolentsev1, N. Vetcha1, and R. Moreau2

1Mechanical and Aerospace Engineering Department, University of California Los Angeles, Los Angeles, California 90095, USA
2Laboratoire EPM, ENSHMG, BP 95, 38402 Saint-Martin d’Hères, France

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(Received 20 January 2011; accepted 14 December 2011; published online 7 February 2012)

In this study, flow phenomena associated with inflectional and boundary-layer instabilities, as well as a mixed instability mode in quasi-two-dimensional magnetohydrodynamic flows in a rectangular duct are accessed with the help of a parametrical model, where the basic velocity profile with near-wall jets and associated points of inflection are produced by imposing an external flow-opposing force. By varying this force, various instability modes and transition scenarios are reproduced. First, linear stability analysis is performed and then nonlinear effects are studied using direct numerical simulation for Hartmann numbers 100 and 200 and Reynolds numbers from 1800 to 5000. A special attention is paid to the location of the inflection point with respect to the duct wall. A more complex flow dynamics, including various vortex-wall and vortex-vortex interactions, and even negative turbulence production are observed and analyzed as the inflection point approaches the wall. The analysis of obtained results and their comparison with relevant data for magnetohydrodynamic duct flows gain an insight into what is typically called “jet instability,” including linear and nonlinear mechanisms.

© 2012 American Institute of Physics

Article Outline

  1. INTRODUCTION
  2. THE MODEL PROBLEM
  3. LINEAR STABILITY ANALYSIS
  4. NONLINEAR COMPUTATIONS
  5. COMPARISONS WITH AVAILABLE DATA
  6. CONCLUSIONS

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KEYWORDS and PACS

Keywords

boundary layer turbulence, flow instability, flow simulation, jets, laminar to turbulent transitions, magnetohydrodynamics, numerical analysis, pipe flow, vortices

PACS

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.3680864

PUBLICATION DATA

ISSN

1070-6631 (print)  
1089-7666 (online)

Publisher

$abstract.society.value is a Member of CrossRef American Institute of Physics

For access to fully linked references, you need to log in.
    M. Kinet, B. Knaepen, and S. Molokov, “Instabilities and transition in magnetohydrodynamic flows in ducts with electrically conducting walls,” Phys. Rev. Lett. 103, 154501 (2009).

    A. Pothérat, “Quasi-two-dimensional perturbations in duct flows under transverse magnetic field,” Phys. Fluids 19, 074104 (2007)PHFLE6000019000007074104000001.

    S. Smolentsev and R. Moreau, “One-equation model for quasi-two-dimensional turbulent magnetohydrodynamic flows,” Phys. Fluids 19, 078101 (2007)PHFLE6000019000007078101000001.


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