Modal dynamics and instability in Rayleigh-Bénard convection
Adam Perkins
Advisor: Michael Schatz |
Adam Perkins
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Abstract
Instabilities play an important role in many physical systems, from weather and geothermal events to biological and chemical systems. In many such systems, knowledge of the dynamically important modes leading to instability is very desirable, whether for forecasting or control. While there have been advances in the computational ability to investigate the dynamical degrees of freedom in high-dimensional systems, most theoretical and numerical investigations fail to account for the effect of real physical boundaries. Moreover, such investigations often use a simplified model of the full set of governing system equations; in fluid convection, for example, the Boussinesq approximation is routinely employed. It is thus very desirable to be able to obtain a quantitative description of the dynamical modes of instability directly from experimental data. However, there exists no general experimental technique for extracting such information from complex systems.
In this talk, I will present results from experiments performed with a Rayleigh-Bénard convection system, a system long considered a paradigm of pattern-forming systems. After introducing the system and some background concepts, I will explain our approach to extracting from experimental data the modes that dominant system dynamics near various instability thresholds. The structures and growth rates of the dominant modes at different locations in the parameter space allow us to draw connections between our localized modes to the theoretical instabilities of an infinite system. I will also discuss briefly a related investigation into the limiting effect of instability on predictive power. This is being done with a recently-introduced efficient forecasting algorithm applied to experimental convection data.
Speaker biography
Adam obtained his undergraduate degree from the University of Northern Iowa before coming to Georgia Tech in 2005. At Tech, Adam joined the Schatz research group, which performs experiments on fluids systems in an attempt to understand complex spatiotemporal dynamics. His research efforts have been in using experiments on a Rayleigh-Bénard convection system to study the mechanisms leading to instability and the possible consequences for predictive ability.
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