A Fluid Dynamics Approach for Assessing the Intelligent Geomorphic Design of the Japanese Pufferfish Nest

Abdulla Jailam Shameem,Manousos Valyrakis,Hossein Zare-Behtash

doi:10.3390/geosciences11010022

Abdulla Jailam Shameem, Manousos Valyrakis + Show 1 more

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https://doi.org/10.3390/geosciences11010022

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Journal: Geosciences	Publication Date: Jan 1, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: University of Glasgow

Abstract

Research into the geometric nests built by white-spotted pufferfish indicated the nest’s potential for flow control and reduction in flow velocity. However, studies to date have only focused on the construction process and behaviour of the male pufferfish. Hence, the form and functions of the unique features of the nest remain unclear. The present study aims to explore the flow features most useful in understanding the habitat conditions of the nest through a combination of photogrammetric reconstructions of the nest features and two-dimensional (2D) computational fluid dynamic simulations. The findings show the role of the nest structure in reducing the flow velocity and shear stress within the nesting site. Analysis of shear stress indicates that male pufferfish build the outer zones of the nest with coarser material that improves the overall shear strength of these areas. The study identified the function of the nest structure in the protection of the eggs through reduction in flow variations and improved aeration. The addition of shell fragments to the nest peaks by the male pufferfish contributes to the resiliency of the nest structure and ensures a stable bed surface at the central zone.

Highlights

Through millions of years of evolution, nature has produced ingenious and practical designs that solve many of today’s technical problems
From drag reduction inspired by sharkskin riblet microstructures [1] to intelligent structures inspired by bee honeycombs [2], researchers are increasingly reliant on bioinspired designs for innovations
Acceleration of the flow is observed as it goes over the first peak of the upstream ridge, forming a dome over the top of the nest with a decrease in the mean flow velocity inside the nest central zone

Summary

Introduction

Through millions of years of evolution, nature has produced ingenious and practical designs that solve many of today’s technical problems. From drag reduction inspired by sharkskin riblet microstructures [1] to intelligent structures inspired by bee honeycombs [2], researchers are increasingly reliant on bioinspired designs for innovations. A recent chance encounter led to the discovery of the white-spotted pufferfish (Torquigener albomaculosus) [3], whose adult males, measuring, on average, 109 mm in total length, have been observed constructing the approximately two-meter-wide circular geometric nests [3,4]. Despite the sheer amount of time and energy it takes to build the structure, and unlike other species that reuse nesting sites [5,6], T. albomaculosus males abandon the nesting site in search of other areas to rebuild the nest The reason for this behaviour is not yet fully understood, Kawase et al [4] put forward a plausi-

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