Investigation of the Protective Collars Effect on the Scour Depth around Fixed Offshore Vertical Pier

Nowadays، the power industry with fixed offshore wind turbines through the renewable energies is one of the progressing industries. The installation of scour protection structures is done against the scouring process. The collars are one of the protective structures. In this study، distribution of the bed shear stress around the pier is investigated via the FLUENT software. The results have been observed based on the relative heights of the collar to the substrate. On the other hand، in a hydraulics laboratory، some experiments have been done on a physical model with and without the protective structures. The charts of the scour depths، the equilibrium scour depths and the patterns of the scour hole around the pier have been obtained for different test scenarios. Finally، comparing of results of the numerical analysis and experimental results showed that there was direct relationship between bed shear stress and the equilibrium scour depths as well as the collars with less height from substrate had proper effect on protection of pier.