LOW-SPEED MANEUVERING HYDRODYNAMICS OF FISH AND SMALL UNDERWATER VEHICLES

The low-speed maneuvering by fish and small underwater vehicles is con sidered. The focus is on fluid engineering rather than on biology. An attempt is made to learn from aquatic animals and apply the distilled knowledge to build maneuvering devices. The work is described in three parts. In the first, the morphology of twenty eight species of fish i s considered. They are classified into three categories: low speed hig hly maneuverable, high speed poorly maneuverable, and an overlapping c ategory, viz., high speed highly maneuverable. The qualitative relatio nship between the length scales of their fins and maneuvering ability is examined. Next, an obstacle-filled aquarium is built and the maneuv ering trajectories of two species of fish that are fast yet maneuverab le, are video-taped and digitized. Their performance are compared with those of small underwater vehicles. In this manner, the maneuvering ' 'gap'' between nature and engineering which appears to be large, is qu antified. Finally, based on their length scales in species of fish tha t are deft in maneuvering, a dorsal-fin based maneuvering device is bu ilt and its behavior is studied.