미세플라스틱 입자 종단속도 측정: 종횡비 변화에 따른 영향 분석

Abstract

Plastic released into the ocean is decomposed into microplastics and threatens human life. Accordingly, research is being conducted to predict the behavior of microplastics for efficient collection and management of microplastics. this paper was conducted to measure the terminal settling velocity through the sinking experiment of microplastics and to help understand the transportation process. The experiment was conducted using spherical particles and non-spherical particles with 7 aspect ratios. Experiments were conducted in two fluids, water and mixed fluid, to deal with a wide range of Reynolds numbers. As the results, it is judged that in the range of 10-1<102, the settling velocity of the particles is affected by the area of the particles subjected to the drag force. In addition, when Re<1, it was confirmed that the influence of the dispersion acting due to the shape of the particles was not large, and when Re>1, it was confirmed that the dispersion acts largely according to the shape of the particles. Accordingly, it is judged that the viscosity of the fluid affects the settling velocity of the particles when Re<1, and when Re >1, the inertia affects the settling velocity of the particles. Based on this, shape factors that can be applied to non-spherical particles of various shapes without limiting the shape of the particles were derived and an empirical equation for the settling velocity was proposed.