Particle inertia is expected to play an important role in the transport, dispersion and accumulation of plastic debris driven by wave-breaking–induced currents and turbulence in the surf zone, particularly for large or dense materials. However, most numerical models still treat plastic debris as passive tracers and are rarely supported by systematic validation. This study proposes a one-way CFD–Lagrangian coupling framework for modeling wave-induced transport of inertial, non-spherical plastic debris spanning micro- to macro-sizes. Wave-induced hydrodynamics is modeled with OpenFOAM®, while debris trajectories are computed with a modified Maxey–Riley formulation that incorporates shape- and oscillatory-flow-dependent drag, added mass, stochastic dispersion, and a probabilistic beaching scheme. The methodology is calibrated and validated against 2DV wave-flume experiments on plastic-debris transport over a dissipative beach under regular spilling waves, covering 15 debris types with contrasting buoyancies/sizes/shapes/flexibilities across two release configurations. Numerical simulations reproduce the cross-shore evolution of concentrations and debris distributions observed in laboratory (RMSE≈0.03–0.10% and R2=0.70–0.99, with slightly larger deviations for a few buoyant elements), confirming that transport and accumulation behaviors are strongly dependent on debris characteristics. Moreover, the Maxey–Riley coefficients calibrated with experimental data show systematic trends: oscillatory drag is inversely correlated with the Keulegan–Carpenter number; added mass depends on debris size and flexibility; and dispersion is strongly anisotropic and increases with turbulence. Overall, the proposed framework extends inertial Lagrangian-tracking models beyond small spherical particles and provides a physically based, computationally efficient tool for investigating plastic-debris dynamics in energetic coastal environments.
Nunez, P., Romano, A., Lara, J.L., Barajas, G., Medina, R., Besio, G. (2026). A CFD-Lagrangian model coupling for the transport, dispersion and accumulation of inertial non-spherical finite-size plastic debris in the surf zone. COASTAL ENGINEERING, 208 [10.1016/j.coastaleng.2026.105009].
A CFD-Lagrangian model coupling for the transport, dispersion and accumulation of inertial non-spherical finite-size plastic debris in the surf zone
Romano A.;
2026-01-01
Abstract
Particle inertia is expected to play an important role in the transport, dispersion and accumulation of plastic debris driven by wave-breaking–induced currents and turbulence in the surf zone, particularly for large or dense materials. However, most numerical models still treat plastic debris as passive tracers and are rarely supported by systematic validation. This study proposes a one-way CFD–Lagrangian coupling framework for modeling wave-induced transport of inertial, non-spherical plastic debris spanning micro- to macro-sizes. Wave-induced hydrodynamics is modeled with OpenFOAM®, while debris trajectories are computed with a modified Maxey–Riley formulation that incorporates shape- and oscillatory-flow-dependent drag, added mass, stochastic dispersion, and a probabilistic beaching scheme. The methodology is calibrated and validated against 2DV wave-flume experiments on plastic-debris transport over a dissipative beach under regular spilling waves, covering 15 debris types with contrasting buoyancies/sizes/shapes/flexibilities across two release configurations. Numerical simulations reproduce the cross-shore evolution of concentrations and debris distributions observed in laboratory (RMSE≈0.03–0.10% and R2=0.70–0.99, with slightly larger deviations for a few buoyant elements), confirming that transport and accumulation behaviors are strongly dependent on debris characteristics. Moreover, the Maxey–Riley coefficients calibrated with experimental data show systematic trends: oscillatory drag is inversely correlated with the Keulegan–Carpenter number; added mass depends on debris size and flexibility; and dispersion is strongly anisotropic and increases with turbulence. Overall, the proposed framework extends inertial Lagrangian-tracking models beyond small spherical particles and provides a physically based, computationally efficient tool for investigating plastic-debris dynamics in energetic coastal environments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
