SPH Simulates Steep‐Stepped Spillway Flows Assessing Convergence, DDT Effects, and Pressure Accuracy

ABSTRACT This study investigates a steep‐stepped spillway with a 1V:0.75H slope using the Smoothed Particle Hydrodynamics method in DualSPHysics. Simulations are validated against experimental data from Olinger and Brighetti and RANS results from Arantes et al. using ANSYS CFX. Convergence is evaluated for different particle spacings, and d p = 0.0015 m is selected as a compromise between accuracy and computational cost based on L 2 ‐norm and mean relative error. The density diffusion term (DDT) is assessed, showing its ability to reduce non‐physical pressure oscillations and improve wall‐pressure predictions consistent with skimming flow. Free‐surface elevations and velocity profiles agree with reference data, especially at high flows. A short collision‐wave transient is identified, allowing separation of numerical start‐up effects from the physical regime and supporting the use of smoothed particle hydrodynamics (SPH) in analysis and design approaches for engineering applications.