A hybrid approach to particle tracking and Eulerian–Lagrangian models in the simulation of coastal dispersion

A hybrid approach to the problem of predicting the dispersion of contaminants (e.g. suspended solids or heated water) in coastal areas is presented. A neutral random walk particle tracking method is adopted in the vicinity of the source point, where steep concentration gradients occur. In the case of heat dispersion particles are assigned with buoyancy, which leads to additive horizontal diffusivity. In the far field, Eulerian–Lagrangian concentration models are used to represent the advection-dominated characteristics of coastal regions. In two simple model tests, the proposed scheme showed reasonable accuracy compared to the analytical solution, especially around the source point where the concentration gradients were high (∇c≥0.005∇c≥0.005). The present results strongly advocate the use of a random walk model for the near field and a Eulerian–Lagrangian concentration model for the entire domain when modeling dispersion of contaminants in coastal waters.