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Speaker: Addie Harrison, Program in Applied Mathematics
Title: Fluid dynamices of nematocysts firing
Abstract: Extrusomes are specialized organelles found in cnidarians, protists, and dinoflagellates that achieve the fastest known acceleration in nature. Their ultra-fast microscale firings present unique fluid dynamic challenges due to viscous-dominated effects and boundary layer interactions. In this presentation, I will discuss how I used the immersed boundary method to numerically simulate the dynamics of multiple barb(s) firing and capsule ejection in two dimensions. For the multiple barb(s) firing model, I examined the influence of firing order, barb spacing, and Reynolds number (Re) on prey contact. Results demonstrate a non-monotonic relationship between the distance from the center barb to the prey and Re. At high Re, inertial forces dominate, ensuring the center barb consistently reaches its target. While at low Re, fluid entrainment carries the barbs further and alters their trajectories. Despite variations in firing order and spacing, prey contact remains robust at high Re, highlighting the resilience of inertial effects in achieving successful contact. In the capsule ejection model, I explored the effects of capsule geometry, gap opening size, and barb material properties on ejection efficiency. Results indicate that smaller gaps and larger capsule minor axes produce higher pressure gradients, accelerating ejection. Additionally, stiffer barbs achieved faster target contact compared to flexible ones. These results provide fundamental insights into the biomechanics of extrusomes and contribute to broader implications in microinjector technology. Join me to explore how nature's fastest accelerators inspire advancements in small-scale injection technology.