Meeting Abstract
Horseshoe crabs (Limulus polyphemus) mate in the surf zone where they are subjected to strong currents and waves. The strong currents can flip the horseshoe crab, exposing its ventral tissues to predation and desiccation. One possible way to prevent flipping is for the shell to produce negative lift (or minimal positive lift) in flow. Elucidating what forces are generated by the shell in flow may inform the engineering design of manmade structures that require lift reduction, as well as improve our understanding of the adaptive morphology of the shell. To quantify flow over the shell and the forces generated, we digitally reconstructed a 3D horseshoe crab using a laser scanner and a juvenile horseshoe crab molt. With the digital file, we 3D printed a physical horseshoe crab model for use in particle image velocimetry (PIV). PIV allows us to experimentally visualize the flow structure for comparison to simulations. The results of the experiment will be used to validate numerical simulations using the immersed (IB) boundary method. The IB simulations will then be used to quantify the forces produced, particularly lift and drag which are essential to understanding flipping. When done across a sweep of angles of attack, PIV and IB together will give a much fuller picture of the forces imparted on and the flow structure around the horseshoe crab than has previously been published.
