Fri, Nov 13, 2020 @ 03:00 PM - 04:00 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Mark Hermes, USC AME PhD Student
Talk Title: Pentaradial sea stars generate downforce
Abstract: Intertidal sea stars often function in environments with extreme hydrodynamic loads that can compromise their ability to remain attached to surfaces. While behavioral responses such as burrowing into sand or sheltering in rock crevices can help minimize hydrodynamic loads, previous work shows that sea stars also alter body shape in response to flow conditions. This morphological plasticity suggests that sea star body shape may play an important hydrodynamic role. In this study, we measured the fluid forces acting on surface-mounted sea star and spherical dome models in water channel tests. All sea star models created downforce, i.e., the fluid pushed the body towards the surface. In contrast, the spherical dome generated lift. We also used Particle Image Velocimetry (PIV) to measure the midplane flow field around the models. Control volume analyses based on the PIV data show that downforce arises because the sea star bodies serve as ramps that divert fluid away from the surface. These observations are further rationalized using force predictions and flow visualizations from numerical simulations. The discovery of downforce generation could explain why sea stars are shaped as they are: the pentaradial geometry aids attachment to surfaces in the presence of high hydrodynamic loads.
Biography: Mark Hermes is a Ph.D. student advised by Dr. Mitul Luhar working in the Fluid-Structure Interactions Lab at University of Southern California (USC). His research explores the intersection of underwater crawling and hydrodynamic shape optimization for surface-attached bodies. Mark received his B.S. in Mechanical Engineering at the University of Texas at Austin and his M.S. at USC.
Host: AME Department
More Info: https://usc.zoom.us/j/92144809085
Audiences: Everyone Is Invited
Posted By: Christine Franks