### Session M20: Instability in Shear Layers

8:00 AM–10:10 AM, Tuesday, November 22, 2011
Room: 323

Chair: Luca Brandt, KTH Royal Institute of Technology

Abstract ID: BAPS.2011.DFD.M20.2

### Abstract: M20.00002 : Enhancement of thermal fluctuations in Plane Couette Flow

8:13 AM–8:26 AM

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#### Authors:

Jose M. Ortiz de Zarate
(Complutense University)

Jan V. Sengers
(University of Maryland)

Mode-coupling phenomena in systems outside equilibrium generically cause an enhancement of thermal fluctuations. These enhancements can be studied by Landau's fluctuating hydrodynamics. Here we present a detailed study for the case of plane Couette flow based on stochastically forced Orr-Sommerfeld and Squire equations. The forcing arises from random contributions to the stress tensor due to the stochastic nature of molecular collisions. This intrinsic stochastic forcing is then amplified by mode- coupling mechanisms associated with the shear flow. We discuss the different coupling mechanisms, the most important one being the direct coupling between fluctuations of the wall-normal velocity and vorticity. The most pronounced effect is amplification of wall-normal vorticity fluctuations with a spanwise modulation at dimensionless wave numbers $q_\parallel$ around 1.5.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.DFD.M20.2