Abstract: Fluid Dynamics of a Nematocyst
Nematocysts are stinging organelles found in organisms such as jellyfish, anemones, and hydrozoans. The firing of the nematocyst represents potentially the largest known acceleration in the natural world. The scale of the acceleration is so large, that the microscale fluid dynamics of its discharge reach the inertial regime. As the barb moves through the fluid to its target, it transitions from the inertial regime to the viscous dominated regime. It is known that the fluid dynamics and drag acting on a sphere in this range are highly dependent upon the Reynolds number (Re) and are difficult to resolve analytically. We have used direct numerical simulation of the Navier Stokes through this Re range to quantify the flow past the barb and the drag forces acting upon it.