Title page for ETD etd-08062006-143058


Type of Document Master's Thesis
Author Einarsson, Magnus Ingi
Author's Email Address igni6@hotmail.com
URN etd-08062006-143058
Title Quantifying Spatio-Temporal Chaos in Rayleigh Benard Convection
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Paul, Mark R. Committee Chair
Tafti, Danesh K. Committee Member
Vick, Brian L. Committee Member
Keywords
  • microextensive chaos
Date of Defense 2006-07-26
Availability unrestricted
Abstract
In this project Rayleigh Benard convection (RBC) in a cylindrical domain with experimentally realistic boundaries was investigated numerically. The results were obtained using

large-scale parallel calculations. The flow field was determined as well as its linearized solutions in order to obtain Lyapunov diagnostics. The emphasis is on the effects that the domain size (gamma) has on the system dynamics (gamma = radius/depth for a cylindrical domain). Temperature fields were viewed for different gamma's and a transition to spiral defect chaos was observed for large gamma's. The temperature and thermal perturbation fields were inspected for gamma = 10 and large perturbations were found to be very localized and caused by small defects in the temperature field. The azimuthal average of thermal perturbations indicate that the perturbations are largest at the boundaries for small domains and largest at the center for

large domains. This suggests that small to intermediate aspect ratio RBC should not be

thought of as a set of weakly correlated regions in space. The leading order Lyapunov exponent was positive over a range of conditions indicating that the system is truly chaotic.

The fractal dimension was calculated for several domain sizes and the system was found to

be extensive even though the system dynamics change significantly.

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