Evaluating the particulate organic matter particles distribution characteristics around artificial reefs using computational fluid dynamics

Abstract

Particulate organic matters (POMs) are small (<1 mm in diameter) and disperse or accumulate along water flow. Their interaction with an artificial reef (AR) is important because it characterises POM accumulation around an AR, where high productivity can be expected. We therefore investigated the spatial distribution characteristics of POMs for three types of ARs (box-type, cylindrical-type, and hemispherical-type), using computational fluid dynamics (CFD). As a result, the distribution patterns of POM particles were clearly distinguished according to the shape of the ARs. The accumulation of POM particles on the analysis plane was highest in the cylindrical-type AR, followed by the box-type and hemispherical-type ARs. Many POM particles were distributed in regions where the turbulence energy was strong. The larger the diameter and density of the POM particles were, the closer they tended to be in regions with strong vorticity. Based on the distribution and behavioural characteristics of the POM particles, e.g., thick region, empty region, transport limit line, main layer, and column, it is possible to determine the placement model for marine fisheries, such as ARs. Therefore, it is possible to create a POM pool that can form the basis of the marine ecosystem by using marine fishing facilities.