Near-body flow dynamics in swimming fish

Area of Science:

• * Biomechanics
• * Fluid Dynamics
• * Ichthyology

Background:

• * Understanding fish locomotion is key to biomimetic design.
• * The giant danio (Danio malabaricus) is studied for its efficient swimming.
• * Propulsion mechanisms in fish involve complex fluid-body interactions.

Purpose of the Study:

• * To investigate the flow patterns and motions during giant danio swimming.
• * To compare experimental data with numerical simulations of fish propulsion.
• * To elucidate the role of fish morphology in efficient thrust generation.

Main Methods:

• * Experimental flow visualization to capture 2D velocity fields.
• * Three-dimensional numerical simulations for total velocity field prediction.
• * Analysis of fish morphology, including the peduncle region and tail articulation.

Main Results:

• * Good agreement between experimental and numerical velocity and vorticity fields.
• * Fish morphology facilitates smooth flow and thrust generation via the articulated tail.
• * Efficient flow actuation by the tail, generating controlled vorticity for propulsion and maneuvering.

Conclusions:

• * Giant danios utilize body-bound vorticity and caudal fin interaction for efficient propulsion.
• * Streamlined near-body flow and controlled vortex shedding enhance swimming efficiency.
• * The interplay between body-generated and fin-generated vorticity is crucial for fish maneuverability.