Dresden 2017 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 57: Posters - Turbulence

DY 57.1: Poster

Thursday, March 23, 2017, 17:00–19:30, P1A

Inclined-layer convection in fluids with small Prandtl number — •Oliver Zier, Werner Pesch, and Walter Zimmermann — Theoretische Physik I, Universität Bayreuth, 95440 Bayreuth, Germany

The onset of thermal convection is strongly modified, if the fluid layer is not perpendicular to gravity and inclined by an angle [1]. In this case the system becomes anisotropic and the basic state is characterized by a cubic shear flow profile. In addition an intricate competition between an buoyancy-driven and a shear-flow driven pattern-forming instability mechanism takes place. The shear-flow driven instability prevails in the case of a small Prandtl number P, on which we focus in this work.

For a finite inclination angle transverse rolls form at threshold with their axes perpendicular to gravity. The secondary instabilities of the rolls with increasing Rayleigh number depend on the inclination angle and are characterized by spatially periodic perturbations along their roll axes. Here we focus on the regime of small inclination angle, where both instabilities compete. As a result, we find in full simulations complex ’heteroclinic orbits’ where the system switches periodically between the two pattern types.

[1] P. Subramanian, O. Brausch, E. Bodenschatz, K. Daniels, T. Schneider, W. Pesch, J. Fluid. Mech. 794, 719 (2016)