*Article* **Propagation of Solitary Waves over a Submerged Slotted Barrier**

#### **Yun-Ta Wu and Shih-Chun Hsiao \***

Department of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan 701, Taiwan; ytwu@mail.ncku.edu.tw

**\*** Correspondence: schsiao@mail.ncku.edu.tw; Tel.: +886-6-275-7575 (ext. 63262)

Received: 24 May 2020; Accepted: 6 June 2020; Published: 9 June 2020

**Abstract:** In this article, the interaction of solitary waves and a submerged slotted barrier is investigated in which the slotted barrier consists of three impermeable elements and its porosity can be determined by the distance between the two neighboring elements. A new experiment is conducted to measure free surface elevation, velocity, and turbulent kinetic energy. Numerical simulation is performed using a two-dimensional model based on the Reynolds-Averaged Navier-Stokes equations and the non-linear *k*-<sup>ε</sup> turbulence model. A detailed flow pattern is illustrated by a flow visualization technique. A laboratory observation indicates that flow separations occur at each element of the slotted barrier and the vortex shedding process is then triggered due to the complicated interaction of those induced vortices that further create a complex flow pattern. During the vortex shedding process, seeding particles that are initially accumulated near the seafloor are suspended by an upward jet formed by vortices interacting. Model-data comparisons are carried out to examine the accuracy of the model. Overall model-data comparisons are in satisfactory agreement, but modeled results sometimes fail to predict the positions of the induced vortices. Since the measured data is unique in terms of velocity and turbulence, the dataset can be used for further improvement of numerical modeling.

**Keywords:** solitary wave; submerged breakwater; slotted barrier; experiment; PIV; RANS model
