(370a) Using the Penalty Immersed Boundary Method to Model the Interaction of Filiform Hairs On Crickets

Fluid-structure interactions are important in a wide range of applications, and they are computationally complex. One such example comes from crickets, which have evolutionarily developed an excellent micro-air-flow sensory system. Understanding principles of the cricket's air-flow sensor will help design and manufacture artificial sensors. This project focuses on improving and validating a Penalty Immersed Boundary (PIB) model of the cricket sensory system. The sensory hairs, called filoform hairs, are located on two appendages, the cerci, at the abdominal end of the cricket. Each cercus has approximately 800 filoform hairs on a full adult. Filoform hairs play many roles for a cricket by detecting and distinguishing air-flow with pertinence in mating and predator defenses. Previous efforts by others have modeled the filoform hair as a rigid inverted pendulum. The PIB method is a modification of the traditional Immersed Boundary (IB) method, which treats the entire domain as fluid and includes ?immersed' boundaries to capture the physical nature of solids mechanically coupled to the fluid, and can accurately model solids with higher densities than a surrounding fluid. Advantages to this approach over previous models include a flexible fluid solver (previous models used an idealized, analytical flow field), the filoform hairs are not completely rigid, and, most importantly, the entire cerci and all the filoform hairs can be modeled. One goal was to improve the precision and accuracy of modeling a single filoform hair by adjusting model parameters so that the model predictions more accurately fit new experimental data. The other goal was to model a portion of a full cercus based on filoform hair data from a real cricket and use the model to determine the interactions occurring between multiple hairs and identify any optimization of the cercal system.