Gliding locomotion of manta rays, killer whales and swordfish near the water surface

Abstract

The hydrodynamic performance of the locomotive near the water surface is impacted by its geometrical shape. For marine animals, their geometrical shape is naturally selective; thus, investigating gliding locomotion of marine animal under the water surface may be able to elucidate the influence of the geometrical shape. We investigate three marine animals with specific geometries: the killer whale is fusiform shaped; the manta ray is flat and broad-winged; and the swordfish is best streamlined. The numerical results are validated by the measured drag coefficients of the manta ray model in a towing tank. The friction drag of the three target models are very similar; the body shape affected form drag coefficient is order as swordfish < killer whale < manta ray; the induced wave breaking upon the body of the manta ray performs different to killer whale and swordfish. These bio-inspired observations provide a new and in-depth understanding of the shape effects on the hydrodynamic performances near the free surface.

Effects of body plan evolution on the hydrodynamic drag and energy requirements of swimming in ichthyosaurs

“…However, three-dimensional dynamic CFD is still computationally expensive and would require a large set of assumptions regarding the kinematics and the geometry of the propulsor elements of ichthyosaurs. Morphology alone has an undeniable effect on drag, as shown by a wealth of aerodynamics research [25,39,40]. Focusing on this, we employed static CFD as the most accurate tool for testing such a wide sample of animals.…”

“…We scaled our models to equal total length and equal volume to estimate the drag per unit volume in ichthyosaurs, both of which are valid scaling criteria to study the hydrodynamic effects of morphology. The former is often the choice for hydrodynamic studies [32,39], because controlling for dynamic similarity avoids the effect of Reynolds number on drag ( C d is smaller at larger Re ) [10]. The latter is used in underwater vehicle research to look for designs with minimum drag for a given load [40,42,43].…”

A study on the hydrodynamic performance of manta ray biomimetic glider under unconstrained six-DOF motion

“…It can easily satisfy the G2 continuity [ 19 ], which means that two connected curves on the model not only share the common point, but also have the same tangential direction, the same binormal vector, and the equal curvature at that common point. The parameters of the glider model (both for computation and for experiments) are determined according to the literature [ 17 ], where the 3D model is rebuilt based on the 2D photos of real manta rays taken from different angles (the source of the photograph is from open-source website http://fishbase.org ). In addition, some essential simplifications and modifications are adopted during model reconstruction; for example, head fins are removed in order to obtain a better streamlined bionic model.…”

“…Zhan et al [ 16 ] conducted a hydrodynamic simulation of a manta ray model that was fixed in the uniform flow to investigate the differences in drag coefficients and lift coefficients corresponding to the current speed and attack angles of the manta ray model. Furthermore, three types of ocean dwellers (killer whales, manta rays, and swordfish) with different body parameters were also studied for near-water gliding motion, and the differences in the hydrodynamic performance of the different body shapes were obtained according to a full-scale (2 m) towing experiment of manta rays [ 17 ]. Wang et al [ 18 ] studied the hydrodynamic performance of the biomimetic manta ray underwater glider numerically.…”

Hydrodynamic Analysis of Bionic Chimerical Wing Planforms Inspired by Manta Ray Eidonomy

“…In contrast to fishes, including sharks, these filter-feeding swimmers have developed a disproportionately large brain to their body weight similar to mammals, which gives them a higher level of capabilities in functionality and behavior [8]. In general, the swimming of a manta ray is performed via a combination of two modes [9]: flapping of its left and right pectoral fins [10] [11] and gliding mode provided by its large and extended planform or sometimes just as a pure gliding mode [12] [13]. As aforementioned, the external geometry of a manta ray, including wing planform shape and the shape of hydrofoil ribs, directly affects the swimming performance of the animal in both flapping and gliding modes.…”