Modelling of drifting object dispersion in linear wave-induced flow

Abstract

The dispersal of drifting objects like plant propagule under wave action can provide important information for the restoration of the plant community in coastal areas. An improved motion equation of the drift under wave action is established by coordinate transformation under the premise that the buoyancy is always perpendicular to the free surface, considering the variation of submerged height and the pressure gradient. Its numerical solution obtained by the fourth order Runge-Kutta method was compared with the experimental results in the literature, and the rationality of the improved motion equation is then verified. Then the perturbation method and Lagrange tracking principle were used to obtain the average longitudinal drift velocity expressed by Stokes drift velocity. The effect of different forces in the motion equations to the longitudinal diffusive motion was analyzed. Finally, the hydrodynamic coefficients affecting the prediction were analyzed, and the results show that the effects of the added mass coefficient and the drag coefficient are mainly reflected in the region with higher wave heights. The findings may provide certain scientific guidance for the restoration of coastal vegetation ecology through natural colonization.