Salinity intrusion is one of the most pressing threats to unconfined coastal aquifers, and its simulation is of great importance for groundwater research and management. This study compared the performances of two computational fluid dynamics (CFD) software applications, ANSYS Fluent 2022 R2 and COMSOL Multiphysics 5.6, in simulating the transport of saltwater in a pilot-scale experimental setup, which was built to recreate two boundary conditions of unconfined aquifers with homogeneous stratigraphy. The experiments were performed until the saline wedge reached a quasi-steady-state condition. Sequential photographs and image analysis were required to record the movement of the saline toe and the saline wedge location. The maximum toe length was achieved under the head-controlled boundary condition, with a toe length of 1.6 m after 7 h of the experiment, and 1.65 m and 1.79 m for the COMSOL and ANSYS Fluent simulations, respectively. The findings evidence that the flux-controlled condition produced a better representation of the saline wedge than the head-controlled condition, indicating good agreement between the CFD simulations and the experimental data. Recommendations for future research include CFD simulations of real coastal aquifers and coupling fluid dynamics with other processes such as land subsidence.

Hydrodynamic performance is an essential factor in the design of a watercraft, and the navigation scenario determines the complexity of its operation. This study aims to identify the effect of speed and length on the hydrodynamic behavior of a semi-planing watercraft in shallow waters. A computational fluid dynamics tool was employed to predict the trim, heave, and resistance parameters of two different hulls: a base hull and a craft with an increased hull length. The two hulls had similar hydrodynamic characteristics. The effects of speed and hull length on these predicted parameters obtained for the two hulls were compared. The results showed a low resistance uncertainty and a reduction in dynamic trim for longer hull lengths. These findings highlight the importance of considering balance and dynamic trim in designing shallow-draft watercrafts to ensure an optimal performance in specific conditions, such as rivers with depth restrictions.