Enhanced 3D Turbulence Modeling Sensitivity Assessment for Real-World River Hydraulics Under Extreme Storm Conditions: A Case Study of the Santa Catarina River, Mexico

This study compares enhanced turbulence models in a natural river channel 3D simu-lation under extreme hydrometeorological conditions. Using ANSYS Fluent and the Volume of Fluid scheme, five RANS closures were evaluated: realizable k–ε, Renor-malization-Group k–ε, Shear Stress Transport k–ω, Generalized k–ω, and Base-line-Explicit Algebraic Reynolds Stress model. A Santa Catarina River in Monterrey, Mexico, segment defined the computational domain, which produced high-energy, non-repeatable real-world flow conditions where hydrometric data was not yet available. Empirical validation was conducted using surface velocity estimations obtained through high-resolution video analysis. All models were realized on validated polyhedral mesh with consistent boundary conditions, evaluating performance in terms of mean velocity, turbulent viscosity, strain rate, and vorticity. Mean velocity predictions matched the empirical value of 4.43 [m/s]. The Baseline model offered the highest overall fidelity in turbulent viscosity structure (up to 43 [kg/m·s]) and anisotropy representation. Simulation runtimes ranged from 10 to 16 h, reflecting a computational cost that increases with model complexity but justified by improved flow anisotropy representation. Results show that all models yielded similar mean flow predictions within a narrow error margin, yet differed notably in resolving low-velocity zones, turbulence intensity, and anisotropy, within a purely hydrodynamic framework that does not include sediment transport.