Dispersion Processes in Weakly Dissipative Tidal Channels

We report the results of an extensive experimental campaign dedicated to analysis turbulent dispersion owing circulations in tidal environments, characterized by a inlet and channel with lateral flats. focus on weakly-convergent weakly-dissipative estuaries or embankments, where internal waters communicate open sea through mouth. Tides are reproduced as single multiple harmonics waves. Particle Image Velocimetry is employed measure two-dimensional surface velocity fields. Large-scale macro-vortices, generated vortex shedding during flood phase from barrier, tend occupy entire flats width completely flushed out ebb phase. In all experiments, intense residual current, shape influenced large-scale vortices, observed. The presence vortices current strongly influences Lagrangian auto-correlation functions corresponding absolute time evolution. Looping auto-correlations signature both periodic forcing ultimately, leading super diffusive regimes. An asymptotic Brownian regime always found for investigated range parameters allowing estimate horizontal coefficients which turn decrease friction parameter be enhanced when semi-diurnal constituents prevail. Finally, particle statistics show regimes depending separations, compared typical injection length scale that seems coincide mouth dimension.