An incompressible SPH numerical model for simulating wave and non-Newtonian mud interaction

• Published in: Coastal engineering (Amsterdam) 2023-10, Vol.185, p.104379, Article 104379
• Main Authors: Hejazi, Kourosh, Soltanpour, Mohsen, Aslani Kordkandi, Abolfazl
• Format: Article
• Language: English
• Subjects: Fluid mud; ISPH; Mass transport velocity; Non-Newtonian fluid; Wave attenuation; Wave-mud interaction
• ISSN: 0378-3839; 1872-7379
• DOI: 10.1016/j.coastaleng.2023.104379

Wave-mud interaction has been investigated in terms of wave attenuation and wave-induced mud mass transport velocities. The wave attenuation over muddy beds is a major consideration for designing near-shore structures as well as for the choice of protection options in the muddy coasts. Also, wave-induced sediment and contaminant transport have a great significance for civil and environmental engineers. The wave-mud interaction has been investigated theoretically and experimentally in several studies, but very few numerical model developments, especially no particle-based model such as SPH model, have been reported in the literature. In this study, a new incompressible smoothed particle hydrodynamics (ISPH) numerical model has been developed to simulate the wave-non-Newtonian mud interaction. A new hybrid kernel function has been proposed and was comparatively investigated with the frequently used SPH kernel functions. An inter-particle average method for interface and a modified water surface treatment have been applied to enhance the simulations. To solve the set of equations, firstly, an intermediate velocity was obtained without enforcing incompressibility. Then, an iterative projection method was used to correct the velocity and particle positions at each time step after solving the Poisson equation for pressure. A sparse Gauss-Seidel (SGS) solver with a successive over-relaxation (SOR) method was used to solve the pressure Poisson equation to avoid large two-dimensional matrices. For hydrodynamic verification, water sloshing in a confined container, and sinusoidal, solitary and non-linear wave propagation were simulated, and the results were compared with the analytical and experimental values. The results showed the capability of the newly developed model for simulating the non-linear terms, and that the hybrid kernel function minimized the approximation errors for the derivatives of functions as well as the pressure field in the simulations. The inter-particle average method for the interface and a modified water surface treatment improved the results in terms of surface wave profile and dissipation rate. Also, the results of wave-mud interaction simulations indicated better agreements with the experimental data in comparison to the theoretical and the results of other numerical simulations reported in the literature. The velocity fields revealed that the presence of a mud layer causes a phase shift in velocity. The results also indicated that the v