Two-dimensional modelling for particles transport in wave field

Abstract

Understanding the transport process of substances (e.g., sediments, or propagules like plant seeds) in wave field is of great significance for the ecological restoration and the maintenance of the species diversity in coastal areas. Based on the linear wave and the multi-scale homogenization theory, an analytical solution for the two-dimensional concentration distribution of particles in wave field has been obtained. The analytically predicted longitudinal dispersion coefficient has been verified by results from the literature, and the mean concentration distribution has been verified by the numerical results based on the random displacement model. Additionally, the effect of the wave orbital motion on the concentration distribution of particles is analyzed. The results indicate that, after a long time evolution, the wave orbital motion has little effect on the longitudinal concentration distributions, while the vertical concentration distribution exhibits periodic variations. Finally, the effects of wave parameters on the vertical uniformity and two-dimensional concentration distribution are discussed. The results demonstrate that as the period increases, the vertical concentration distribution becomes more uniform. The maximum of the concentration cloud decreases with increasing wave height. With the increase of water depth, the positions of the peak concentration on the free surface move in the downstream, and those at the water bottom move in upstream directions, respectively. The findings about the spatial and temporal evolution of the particles within the wave field can provide quantized assessment of ecological conditions in coastal wetlands, and provide scientific guidance for ecological restoration.