Three-dimensional numerical simulations on wind- and tide-induced currents: The case of Augusta Harbour (Italy)

Abstract

a b s t r a c tThe hydrodynamic circulation in the coastal area of the Augusta Bay (Italy), located in the eastern part of Sicily, is analysed. Due to the heavy contamination generated by the several chemical and petrochemical industries active in the zone, the harbour was declared a Contaminated Site of National Interest. To mitigate the risks connected with the industrial activities located near the harbour, it is important to analyse the hydrodynamic circulation in the coastal area. To perform such analysis, a parallel 3D numerical model is used to solve the Reynolds-averaged momentum and mass balance, employing the k-ε turbulence model for the Reynolds stresses. The numerical model is parallelized using the programing technology -Message Passing Interface (MPI) and applying the domain decomposition procedure.The Augusta Bay circulation is mainly due to the relative contribution of the wind force acting over the free surface and the tidal motion through the mouths. Due to the geometric complexity of the domain and the presence of several piers along the coast, a curvilinear boundary-fitted computational grid was used, where cells corresponding to land areas or to wharfs were excluded from the computation. Comparisons between numerical results and field measurements were performed. Three different simulations were performed to selectively isolate the effect of each force, wind and tide, acting in the considered domain. The current in the basin was successfully estimated on the basis of the numerical results, demonstrating the specific role of wind and tidal oscillation in the hydrodynamic circulation inside the harbour.

Three-Dimensional Modeling of Wind- and Temperature-Induced Flows in the Icó-Mandantes Bay, Itaparica Reservoir, NE Brazil

“…On the other hand, the wind had a much higher impact on the velocities-up to more than one order of magnitude. This is in agreement with De Marchis et al [15] and Fenocchi et al [13], who as well observed an increase of flow velocities of one order of magnitude in the case of wind and especially during storm events. For the density-induced flow, a velocity increase took place to a lower extend in some specific zones, e.g., on the bottom and superficial layers next to the lateral boundaries, while there was a general decrease at the intermediate water depths.…”

“…The results of the WIND and the HEAT scenarios, compared with the reference REF, showed that strong wind and density changes had an impact on the flow field, confirming a wide range of previous studies (e.g., [6,12,13,15,19]). On the one hand, while the configuration of the flow following the SE wind was maintained over time both horizontally and vertically, the imposed constant ∆T equal to 10 • C changed it substantially (e.g., the flow in the surface layers was induced from the shallow to the deeper waters).…”

“…2000 m 3 /s), which did not allow a stable stratification in the flow field concerning that part; • large parts of the bay are shallow (see Figure 2) and highly influenced by the SE wind (usual ranges as for REF, with daily higher or lower peaks), contributing also to the vertical water mixing (in agreement with e.g., De Marchis et al [15]); • according to Boehrer and Schultze [12], stratification can be established in the warm season if the lake is sufficiently deep (which is not the case here). Additionally, lakes are found to behave like an epilimnion (to be well mixed), in response to strong temperature gradients between water and air (10 • C in this case).…”

“…Only a limited number of CFD simulations for temperature distribution in shallow and small inland water bodies in semi-arid areas can be generally found [19]. As addressed by numerous experts [6,12,15,19], weather conditions (wind, temperature) influence currents and stratification in reservoirs, whose hydrodynamic processes and thermal state are the main drivers of their ecosystem. The classification of lakes according to their circulation patterns has proven to be very useful for limnology assessments [12,30].…”

“…Since wind is considered responsible of hydrodynamic mixing in water bodies and of the relevant increase of flow velocities during storms in shallow lakes [13,15], does the wind (moderate wind, windstorms) significantly influence the three-dimensional flow circulations also in the Icó-Mandantes Bay and in which way? How do the flow velocities change and to which extent?…”