Meeting Abstract

8.4  Saturday, Jan. 4 08:24  The Iridescent Catfish (Pangasianodon hypophthalmus) as a Hybrid Rigid-Undulatory Model for Aquatic Robotics WARD, K/S*; AKANYETI, O; LIAO, J/C; University of Florida; University of Florida; University of Florida, Dept. of Biology jliao@whitney.ufl.edu

At over 32,000 species, fishes can provide a rich source of inspiration for the design of undulatory aquatic robots. One challenging constraint is to establish a platform geometry that accommodates space to house electronic hardware while still preserving an efficient, propulsive body wave. The swimming kinematics and energetics of rainbow trout (Oncorhynchus mykiss) have been well documented and have inspired several robotic designs in the past. Here we investigate the swimming efficiency of another riverine species, the Southeast Asian catfish Pangasianodon hypothalamus, which has a larger, rigid region that is more conducive to housing electronics (almost 50 percent of the rostral body compared to 20 percent in trout). We calculated catfish swimming kinematics and energetics over a range of speeds from 2 to 80 cms^-1 total length = 6.26 ± 0.71 cm, n= 6 fish) and compared them to rainbow trout. We found that catfish consistently have a tail beat amplitude that is about half of the magnitude seen in trout. At swimming speeds less than 20 cms^-1, both species have comparable tail beat frequencies and body wave speeds. At speeds above 20 cms^-1, the body wave speed and tail beat frequency in catfish are lower than that of trout. At lower flow speeds, catfish have a smaller body wavelength than trout, but this value increases to approach the body wave value of trout at higher flow speeds. Overall, at swimming speeds less than 20 cms^-1 catfish have a comparable swimming (e.g. Froude) efficiency to trout. However, at higher swimming speeds, catfish demonstrate lower drag coefficients and therefore swim more efficiently than trout. Our experimental analysis illustrates the power of comparative studies in providing fundamental insight for designing new bio-inspired, undulatory underwater robots.