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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING, no.4, 2025 (SCI-Expanded)
Marine outfall systems are often used for the safe disposal of brine, which is the byproduct of desalination processes, consisting of high concentrations of salt. It is of vital importance to obtain a sufficient dilution to avoid negative impacts that brine might cause on marine ecosystems, such as abrupt changes in salinity, temperature, and densities of ambient waters. Hydraulic design of the diffusers is highly important for a sufficient dilution efficiency, while it is very crucial to understand the behavior of dense jets to make a proper diffuser design. For this reason, analysis of brine jet geometries, their behavior, and mixing and dilution processes within the near-field region is of utmost importance. In this paper, the effects of different diffuser designs under certain discharge conditions on brine jet geometry, behavior, and dilution were investigated using three-dimensional Computational Fluid Dynamics models. First, a reference model was created and calibrated using the results of an experiment that had been previously conducted. Then, based on this calibrated model, different models were created, and, in each model, only one discharge parameter was changed, and the rest were kept the same as the previous model to see the effects of the differing parameters on brine jet geometry, behavior, and dilution. Results revealed that discharge angle, number of ports, port spacing and diameters, and jet velocity significantly affect brine jets' shape, behavior, and mixing and dilution processes. The configuration where there is only one port with 60 degrees inclination yielded the best dilution value of 99.68%.