relatively low thermal conductivity compared to that of the fluid, such as water on plastic, in the CR, CA, SS and SJ modes of evaporation. Magnetic Feature Detection through Coronal Volume Segmentation along Quasi-separatrix Layers Roger Scott - University of Dundee David Pontin Interchange reconnection is thought to play an important role in driving the dynamics of the slow solar wind. In order to understand the details of this process, it is important to catalog the various magnetic structures that are present at the open-closed flux boundary. To this end we have developed a method for identifying discrete flux domains using watershed segmentation along quasi-separatrix layers. In this way we are able to identify structures within the corona that affect the character of the open-closed boundary. By analyzing an assortment of global field models we can then build up a catalogue of common configurations and create a hierarchy for evaluating each one's relevance to the process of interchange reconnection. This, in turn, informs our understanding of which configurations should be given priority for upcoming numerical experiments, and how the results of these
experiments can be brought together to form a more complete picture of the global evolution of the slow solar wind. A Bifurcation Analysis of Spiral Waves using a FitzHugh-Nagumo Model Shreya Sehgal - Liverpool Hope University Andrew Foulkes Spiral waves are spatio-temporal solutions to reaction-diffusion system of equations which have been observed in a wide variety of biological, chemical and physical systems, both artificial and in nature. There are several types of motion of spiral waves. In the simplest case, a free spiral rotates rigidly while its tip describes a circular trajectory. It was also observed that under certain conditions a spiral tip meanders rather than following a periodic circular orbit. Meandering is often not a random motion, rather the spiral tip traces a path resembling an epicycloid, exhibiting flower-like patterns. It is a type of quasiperiodic motion. It has been shown numerically by other authors that a supercritical Hopf bifurcation is responsible for the transition from rigid rotation to meander. However, these studies were limited to small core spirals. In this project, we calculate the dynamics of the spiral wave in a co-moving frame of reference where the core of the spiral never approaches the boundaries of the computation box and it allows the computations of large core spirals using small numerical grids. This leads to a system of reaction- diffusion-advection equations in which the tip of the spiral wave is fixed in position and orientation. We conducted the bifurcation analysis of spiral waves by studying the underlying limit cycles of meandering spiral waves using the FitzHugh-Nagumo system of equations. Results show that indeed a Hopf bifurcation is responsible for the transition from rigid rotation to meander.
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