Proceedings of International Structural Engineering and Construction, 8(1), 2021 Interdisciplinary Civil and Construction Engineering Projects Edited by El Baradei, S., Abodonya, A., Singh, A., and Yazdani, S. Copyright © 2021 ISEC Press ISSN: 2644-108X www.doi.org/10.14455/ISEC.2021.8(1).CEN-01 CEN-01-1 MODELING COMPLEX FLOW INDUCED BY WATER WAVES PROPAGATION OVER SUBMERGED SQUARE OBSTACLES MONA A. TAWAB 1 , TAMER HESHMAT 2 , and ANDREAS SCHLENKHOFF 3 1 Smart Engineering Systems Research Center (SESC), Nile University, Giza, Egypt, 2 Smart Engineering Systems Research Center (SESC), Nile University, Giza, Egypt, Secondment from Cairo University, 3 Hydraulic Engineering Section, School of Architecture and Civil Engineering, Bergische Universität Wuppertal, Wuppertal, Germany Submerged breakwaters are efficient structures used for shore protection. Many design features of these structures are captured upon modeling wave propagation over submerged square obstacles. The presence of separation vortices and large free surface deformations complicates the problem. A multiphase turbulent numerical model is developed using ANSYS commercial package. Careful domain discretization is done employing suitable mesh clustering to capture high gradients. Various numerical model parameters are provided, including grid size and time step. Special attention is directed towards clarifying turbulence initial conditions. Stable simulation results are obtained within acceptable computational time. Numerical results are validated quantitatively using subsurface measurements. Comparison along continuous horizontal and vertical velocity profiles is provided. Temporal and spatial model resolutions are illustrated for three test cases. The effect of wave period and height is well focused. The unsteady vortical structure is visualized. The incident wave energy is calculated and validated against theoretical values. The wave energy dissipation characteristics are briefly explained. Keywords: CFD, Turbulence, Vortex, Multiphase, Breakwater, PIV. 1 INTRODUCTION Accurate simulation of breakwaters is crucial to ensure safety during hostile sea conditions. Towards this goal modeling water waves possess the utmost importance (Goda 2000). Specifically, submerged breakwaters provide considerable shore protection while providing a clear sea view (Johnson et al. 2005). Analysis of wave propagation over submerged obstacles captures many features of real submerged breakwaters. However, two main challenges of the problem are: separation vortices, and strong free surface deformation. Both phenomena occur near relatively large-sized obstacles (Kasem et al. 2010). Accurate modeling of the turbulent rotational flow field is necessary to quantify wave energy dissipation. Hence, turbulent, and multiphase models are needed to capture the problem physics. Developing these models is a nontrivial task. The challenges include fine discretization needed to achieve accuracy, avoiding the effects of reflected waves, and suitable turbulence initial conditions. Suitable grid clustering is crucial to perform transient simulations within acceptable durations. Specifically, clustering is needed near high gradients regions.