Hydrodynamic shape optimization of an auxiliary structure proposed for circular bridge pier based on a developed adaptive surrogate model

Abstract

Reducing the hydrodynamic force for a cylindrical structure is extremely important in oceanic engineering applications. In this study, an auxiliary structure, shaped by two controlling parameters, is proposed to be placed in front of a typical circular bridge pier, desiring to mitigate the hydrodynamic loads on the pier. Two-dimensional numerical simulations are carried out through the open source CFD (computational fluid dynamics) program OpenFOAM to optimize the shape of the auxiliary structure by using a developed adaptive surrogate model, where the optimal auxiliary structure is identified by searching optimal hydrodynamic indexes, i.e., the drag and lift coefficients. The salient observations show that: (1) High efficiency is embodied in the whole optimization procedure by way of adopting the developed adaptive model; (2) The optimal auxiliary structure is featured with convex surfaces and can reduce the vortex scale and accelerate the vortex dissipation; (3) Investigation of the hydrodynamic performance proves that the optimal auxiliary structure can effectively decrease the drag and lift coefficients; and (4) The excellent performance emanating from the optimal auxiliary structure retains for a large range of the Reynolds numbers. It is hoped that the presented concept of the optimal auxiliary structure can provide guidance on mitigating the hydrodynamic loads for other oceanic engineered structures.