Berkeley Fluids Seminar

University of California, Berkeley

Bring your lunch and enjoy learning about fluids!

Monday, October 30, 2017

12:00-13:00, 3110 Etcheverry Hall

Dr. Priya Subramanian ( University of Leeds, UK)

Formation and Spatial Localization of Phase Field Quasicrystals



Abstract: The dynamics of many physical systems often evolve to asymptotic states that exhibit spatial and temporal variations in their properties such as density, temperature, etc. Regular patterns such as graph paper and honeycombs look the same when moved by a basic unit and/or rotated by certain special angles. They possess both translational and rotational symmetries giving rise to discrete spatial Fourier transforms. In contrast, an aperiodic crystal displays long range order but no periodicity. Such quasicrystals lack the lattice symmetries of regular crystals, yet have discrete Fourier spectra. We look to understand the minimal mechanism which promotes the formation of such quasicrystalline structures arising in diverse soft matter systems such as dendritic-, star-, and block co-polymers using a phase field crystal model. Direct numerical simulations combined with weakly nonlinear analysis highlight the parameter values where the quasicrystals are the global minimum energy state and help determine the phase diagram. By locating parameter values where multiple patterned states possess the same free energy (Maxwell points), we obtain states where a patch of one type of pattern (for example, a quasicrystal) is present in the background of another (for example, the homogeneous liquid state). In a bifurcation diagram such localized states fall on solution branches that undergo homoclinic snaking and they can be obtained through numerical continuation.



Bio: Dr. Priya Subramanian completed her PhD on ‘Dynamical systems approach to the investigation of thermoacoustic instabilities in 2012. Since then she has worked at the Max Planck Institute for Dynamics and Self-Organization and is currently a research fellow at University of Leeds. Her research interests focus on spatio-temporal pattern formation in a variety of systems such as thermoacoustic, inclined layer convection and soft matter crystallization systems along with investigations into the emergent dynamics in active fluids. She is a L'Oreal-UNESCO Women in Science UK fellow for this year working on `Mathematical recipes for never-repeating quasicrystals’.




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