ICCE 2022

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EXPERIMENTAL STUDY OF LAGRANGIAN MIXING IN WEAKLY DISSIPATIVE TIDAL CHANNELS. (2023). Coastal Engineering Proceedings, 37, management.33. https://doi.org/10.9753/icce.v37.management.33


Estuaries are extremely dynamic environments, allowing wildlife to grow in a wide variety of ecosystems because of the interaction of masses of water with different characteristics. In particular, coastal bays and estuaries are characterized by flows driven by hydraulic unbalance such as baroclinic pressure gradients, river inflows and wind stresses, and tidal waves. Here, following a reductionist approach, we examine dispersion processes in a physical model of a tidal channel bounded by an inlet mouth, with tides as the dominant forcing. The presence of a tidal inlet can generate macro-vortices that during a tidal cycle may influence the momentum and mass transport on relatively large distances (Awaji et al. (1980), Awaji (1982), Branyon et al. (2022)). Moreover, tides tend to produce non-monotonic particle velocity correlation leading to possible particle looping trajectories that also reflect on a looping character of the Lagrangian integral time scales, differently from the classical statistically steady or homogeneous turbulence (Enrile et al. (2019)). Our goal is to examine the dispersion regimes by means of two-dimensional velocity measurements at the free surface reproduced in a large-scale physical model as a starting point for Lagrangian analysis. We show how the presence of a tidal inlet generates complex flow patterns depending on the character of the forcing tides. Furthermore, the mixed nature of tides may be crucial to dispersion processes, as it enhances the ability of the flow to transport mass in the direction of the main flow.


Awaji, T., Imasato, N., & Kunishi, H. (1980). Tidal exchange through a strait: A numerical experiment using a simple model basin. Journal of Physical Oceanography, 10(10), 1499-1508.

Awaji, T. (1982). Water mixing in a tidal current and the effect of turbulence on tidal exchange through a strait. Journal of Physical Oceanography, 12(6), 501-514.

Branyon, J., Valle-Levinson, A., Mariño-Tapia, I., & Enriquez, C. (2022). Intratidal and Residual Flows Around Inlets of a Reef Lagoon. Estuaries and Coasts, 45(1), 63-77.

De Leo A, Enrile F and Stocchino A (2022) Periodic Lagrangian Coherent Structures around a tidal inlet. Front. Mar. Sci. 9:959304. doi: 10.3389/fmars.2022.959304

Enrile, F., Besio, G., Stocchino, A., & Magaldi, M. G. (2019). Influence of initial conditions on absolute and relative dispersion in semi-enclosed basins. Plos one, 14(7), e0217073.

Haller, G., Hadjighasem, A., Farazmand, M., & Huhn, F. (2016). Defining coherent vortices objectively from the vorticity. Journal of Fluid Mechanics, 795, 136-173.

Haller, G., & Yuan, G. (2000). Lagrangian coherent structures and mixing in two-dimensional turbulence. Physica D: Nonlinear Phenomena, 147(3-4), 352-370.

Shadden, S. C., Lekien, F., & Marsden, J. E. (2005). Definition and properties of Lagrangian coherent structures from finite-time Lyapunov exponents in two-dimensional aperiodic flows. Physica D: Nonlinear Phenomena, 212(3-4), 271-304.

Toffolon, Vignoli, & Tubino (2006). Relevant parameters and finite amplitude effects in estuarine hydrodynamics. Journal of Geophysical Research: Oceans, 111 (C10).

LaCasce, (2008). Statistics from lagrangian observations. Progress in Oceanography, 77 , 1-29.

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Copyright (c) 2023 Annalisa De Leo, Nicoletta Tambroni, Alessandro Stocchino