# Yaw Control Strategies Through Flow Structuring in Carangid C-Type Maneuvers

## TL;DR

This study explores how carangiform fish perform sharp turns by analyzing body movements and fluid dynamics during escape maneuvers.

## Contribution

The study reveals a novel yaw control strategy in fish C-turns based on inertial dominance and body deformation.

## Key findings

- Large-angle turns (>140°) involve higher initial and sustained speed during maneuvers.
- Body deformation correlates linearly with turning angle for yaw angles exceeding 60°.
- Vortex dynamics and pressure gradients support inertial dominance as a key control mechanism.

## Abstract

C-type maneuvers (abbreviated as C-turns), a crucial escape response from for carangiform fish, are investigated to elucidate their yaw control mechanism. High-speed photography coupled with image processing was used to quantify the time-varying midline curvature during C-turns of adult zebrafish (Danio rerio). Self-propelled simulations replicated the motion, resolving the evolving vorticity field and pressure gradients. Statistical analyses revealed a pronounced linear correlation between body deformation and total turning angle for yaw angles exceeding 60°. Notably, large-angle turns (>140°) exhibited both higher initial speed and sustained greater mean speed throughout the maneuver, indicating that achieving substantial yaw not only relies on enhanced body deformation, but also, critically, on inertial dominance persisting throughout the unsteady hydrodynamic interaction. The vortex dynamics and pressure distributions obtained form simulations corroborate the inferred control strategy rooted in this inertial dominance.