Low-Speed Maneuvering Hydrodynamics of Fish and Small Underwater Vehicles

Abstract

SYNOPSIS.The understanding of fish maneuvering and its application to underwater rigid bodies are considered. The goal is to gain insight into stealth. The recent progress made in NUWC is reviewed. Fish morphology suggests that control fins for maneuverability have unique scalar relationships irrespective of their speed type. Maneuvering experiments are carried out with fish that are fast yet maneuverable. The gap in maneuverability between fish and small underwater vehicles is quantified. The hydrodynamics of a dorsal fin based brisk maneuvering device and a dual flapping foil device, as applied to rigid cylindrical bodies, are described. The role of pectoral wings in maneuvering and station keeping near surface waves is discussed. A pendulum model of dolphin swimming is presented to show that body length and tail flapping frequency are related. For nearly neutrally buoyant bodies, Froude number and maneuverability are related. Analysis of measurements indicates that the Strouhal number of dolphins is a constant. The mechanism of discrete and deterministic vortex shedding from oscillating control surfaces has the property of large amplitude unsteady forcing and an exquisite phase dependence, which makes it inherently amenable to active control for precision maneuvering. Theoretical control studies are carried out to demonstrate the feasibility of maneuverability of biologically inspired bodies under surface waves. The application of fish hydrodynamics to the silencing of propulsors is considered. Two strategies for the reduction of radiated noise are developed. The effects of a reduction of rotational rate are modeled. The active cambering of blades made of digitally programmable artificial muscles, and their thrust enhancement, are demonstrated. Next, wake momentum filling is carried out by artificial muscles at the trailing edge of a stator blade of an upstream stator propulsor, and articulating them like a fish tail. A reduction of radiated noise, called blade tonals, is demonstrated theoretically. FIG. 1. Definition of length scales of a fish. FIG. 2. Morphology of dorsal fins of fish families.

The use of morphometric analysis to predict the swimming efficiency of two Neotropical long-distance migratory species in fish passage

“…This factor is considered one of the primary determinants of survival because it defines the ability of the fish to conduct activities in which swimming is involved (Beamish, 1978;Plaut, 2001). Swimming performance can be influenced by the locomotion pattern, body size, shape, physiology, temperature and behavior (Beamish, 1978;Videler & Wardle, 1991;Hammer, 1995) and can limit the use of the habitat by a species (Sambilay, 1990;Bandyopadhyay et al, 1997;Gerstner, 1999).…”

Numerical Study on Motion Simulation with Control Algorithm of Biomimetic Underwater Vehicle

“…The motions of the mechanical pectoral fin can be expressed or characterized using the three angles in (1). Correspondingly, changing the related angular parameters can constitute the so-called drag-based and lift-based swimming mode.…”

“…The four fins exhibit the same motion. The motions of the mechanical pectoral fin are expressed using the three angles represented in (1). The values of the parameters represented in (1) in the drag-based swimming mode(Case1), φ R0 , φ RA , Δφ R , φ FE0 ,, φ FEA φ FL0 , φ FLA and Δφ FE are assumed as 30°, 30°, 0°, -30°, 30°, 0°, 20°, and 90°, respectively ; the corresponding parameters in the lift-based swimming mode(Case2) are assumed as 0°, 0°, 0°, -90°, 30°, 0°, 30°, and 30°.…”

“…It is probable that the introduction of pectoral fin motion to underwater vehicle could improve the performance of them. Consequently, some underwater vehicle with flapping foils and other fish-like control devices attached to rigid cylinders have been developed [1][2] [3].…”

Morphological differentiation among migratory fish species from the Paraná River basin

“…Differences in the shape and length of caudal peduncle are known as important attributes related to swimming ability (Bandyopadhyay et al 1997), and the propulsive force is related to the width of the caudal peduncle (Gosline 1971). The species P. granulosus and P. pirinampu, group IV, have higher maximum width of the body and narrower caudal peduncle causing decrease of the waves provoked by the movement of the anterior region of the body associated with a high caudal fin that promote greater thrust (Aleev 1969).…”