This research, funded by the National Science Foundation, is discovering efficient hydrodynamic thin-shell structural forms that have broad application to coastal resilience (e.g. seawalls/floodbarriers, breakwaters, coastal bridges, and coastal building facades). In addition to advancing knowledge in water structure interaction, this research also demonstrates new integrated analyses methods that include hydrodynamic analyses (using SPH), finite element structural analyses, and machine learning (e.g. neural networks), and numerical optimization (e.g. multi-objective Bayesian optimization) tools. These tools can find optimized forms and develop predictive pressures given wave characteristics.  Since thin-shell structures could be susceptible to dangerous impulse (impact) forces of breaking waves, the numerical approach includes Lagrangian-based two-phase (water and air) smoothed particle hydrodynamic models.  These complex models are validated with two experimental programs: small scale at nearby Stony Brook University and the large scale at the NHERI site in Oregon State.  

Based on results examining pressure and wave impact visualization of inclined walls, it can be concluded that both multiphase (two-phase) and single-phase approaches in DualSPHysics are able to simulate a breaking wave impact with good similarities to experimental observations, albeit with slight modification for single-phase approach. The multiphase approach was more accurately able to capture the short duration of impact pressures. [1, 2]

Numerical SPH and experimental studies were performed on a variety of straight-edged, concave-edged, and convex-edged structural forms for a variety of wave characteristics. Bayesian optimization studies have been performed with two objective functions: reducing force on structure and increasing wave attenuation. It was found that concave forms produce smaller quasistatic forces than convex forms.  Further, for some wave characteristics, ‘discontinuities’ such as corners in T-shaped sections, can cause large impulsive forces. [3, 4, 5]

Numerical SPH and experimental studies were performed on perforated edges. Preliminary numerical results show that the perforations can reduce or eliminate the impulsive force at discontinuities (such as T-shapes) and the relationship between perforation area and force on structure is linear. The experimental data on perforated tests in OSU is in the process of being analyzed. 

1. Pawitan, K., Wang, S., Garlock, M.E.M. (2024). “Multiphase SPH Analysis of a Breaking Wave Impact on Elevated Structures with Vertical and Inclined Walls”, Applied Ocean Research, Vol. 142. https://doi.org/10.1016/j.apor.2023.103832

2. Pawitan, K., Garlock, M., Wang. S. (2024). “Numerical Exploration on The Influence of Wall Inclination to Impulsive Wave Loads on an Elevated Structure”, Proceedings of the 38th International Conference on Coastal Engineering, Rome, Italy.

3. Wu G, ElDarwich H, Pawitan KA, Garlock M. “An SPH Study of Cross-sectional Shape Effects on Coastal Structures Subject to Regular Wave Forces.” Ocean Engineering. Submitted 2025, Under 2nd review.

4. Wu, G., Pawitan, K., Garlock, M. (2024). “Coastal Hazard Mitigation via Structural Shape Modification: Investigating the Influence of Curved Structural Cross-sections on Wave Forces using SPH Modeling”, Proceedings of the 38th International Conference on Coastal Engineering, Rome, Italy.

5. ElDarwich, H., Pawitan, K., Garlock, M. (2024). “Investigation of Hyperbolic Paraboloid Face Profile Efficacy for Free-Surface Breakwaters”, Proceedings of the 38th International Conference on Coastal Engineering, Rome, Italy.