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This work is part of a research program designed to develop a maneuvering propulsor for AUVs (Autonomous Underwater Vehicles) based on the mechanical design and performance of fish fins. Fishes are notable for their ability to maneuver and to accurately position themselves even in highly unsteady flows. Fish can maneuver in tight spaces and accelerate and decelerate quickly from rest or low speed with the same propulsion system. Also, fish fins are remarkable fluid control devices with supporting bony elements that are under active muscular control. In addition to muscular actuation at the base of the fin which governs overall fin position, fish fins possess a bilaminar design that allows active control of propulsor surface curvature. Fish fins can thus actively resist hydrodynamic bending forces during propulsion and maneuvering.
This ongoing effort is specifically focused on understanding the hydrodynamic performance of the pectoral fin of the bluegill sunfish through a combined experimental-numerical approach. Bluegill sunfish has been studied experimentally at Lauder Laboratory (http://www.people.fas.harvard.edu/~glauder//) by Peter Madden and Prof George Lauder.The hydrodynamic performance of the bluegill’s pectoral fin is examined computationally by carrying out a set of simulations using experimentally recorded kinematics at GWU. Proper Orthogonal Decomposition (POD) analyses have been used to extract the essential features of the complicated fin motion so that it can be incorporated into the bio-robotic fin design. POD analyses have taken a step further carrying out CFD simulations. This approach has potential to connect the specific features of the fin motion to the hydrodynamic performance. CFD also helps to answer most “what if” questions that lead us to significant insight into the underlying physical mechanisms of the fin hydrodynamics. A couple of bio-robotic fins have been designed based on the fish mechanical properties and CFD results of POD synthesized gaits by Bio Instrumentation Laboratory at MIT which is our other collaborator in this project.(http://bioinstrumentation.mit.edu/Projects/CP/AUV.aspx)
Personnel: Meliha Bozkurttas, Dr. Haibo Dong