Hydrodynamics of In-Canopy Flow in Synthetically Generated Coral Reefs Under Oscillatory Wave Motion

TL;DR

This study investigates the complex flow dynamics within synthetic coral reefs under oscillatory waves, revealing energy dissipation and momentum transfer patterns crucial for understanding reef hydrodynamics.

Contribution

It introduces a turbulence-resolving computational approach to analyze in-canopy flow in complex coral reefs, an area previously underexplored.

Findings

Turbulent kinetic energy dissipation mainly occurs below reef top and above the Stokes boundary layer.

Vertical Reynolds stress peaks contribute to downward momentum flux during wave cycles.

Most in-canopy turbulence is confined to specific regions related to reef morphology.

Abstract

The interaction of oscillatory wave motion with morphologically complex coral reefs showcases a wide range of consequential hydrodynamic responses within the canopy. While a large body of literature has explored the interaction of morphologically simple coral reefs, the in-canopy flow dynamics in complex coral reefs is poorly understood. This study used a synthetically generated coral reef over flat topography with varying reef height and density to understand the in-canopy turbulence dynamics. Using a turbulence-resolving computational framework, we found that most of the turbulent kinetic energy dissipation is confined to a region below the top of the reef and above the Stokes boundary layer. The results also suggest that most of the vertical Reynolds stress peaks within this region positively contribute to the down-gradient momentum flux during the forward phase of the wave cycle. These findings shed light on the physical relationships between in-canopy flow and morphologically complex coral reefs, thereby motivating a further need to explore the hydrodynamics of such flows using a scale-resolving computational framework.