Aquatic animals (Physiology)

Flow Structure and fluid transport via advection around pectoral fin of larval ZebraFish
are studied numerically using Immersed Boundary Method, Lagrangian Coherent
Structure, passive particle tracing, vortex core evolution and four statistically defined
mixing numbers. Experimental fish kinematics for nominal swimming case are obtained
from previous researchers and numerically manipulated to analyze the role of different
body motion kinematics, Reynolds number and fin morphology on flow structure and
transport. Hyperbolic strain field and vortex cores are found to be effective particle
transporter and their relative strength are driving force of varying flow structure and fluid
transport. Translation and lateral undulation of fish; as a combination or individual entity,
has coherent advantages and drawbacks significant enough to alter the nature of fluid
advection. Reynolds number increase enhances overall fluid transport and mixing in varying order for different kinematics and nominal bending position of fin has average
transport capability of other artificially induced fin morphology.

The hydrodynamics of three different shark heads: Eusphyra blochii (Winghead shark), Carcharhinus acronotus (Blacknose shark) and Sphyrna tiburo (Bonnethead shark) were investigated. Force transducer measurement was used to explore how the cephalofoil (wing-shaped head) affects maneuverability and efficiency. As the dynamic behavior of maneuvering wings differs from that of the steady state motion, experiments have been conducted to simulate: 1) steady-state (no yaw motion) constant velocity swimming, 2) constant forward velocity with yawing motion of the head and 3) turning maneuvers. Different range of velocities, angle of attack, yaw frequency and yaw amplitude were tested. Drag and lift coefficients were calculated and compared. The lift coefficient of Winghead shark is much higher compared to the other sharks. The lift-to-drag ratio showed that the Winghead shark has a hydrodynamic advantage compared to Blacknose shark and Bonnethead shark.