Optimization of catenary risers with hydrodynamic dampers

Abstract

This study presents an optimization process on the design of an improved steel catenary riser configuration with hydrodynamic dampers that seek to minimize the effects caused by compression waves along the risers. The dimensions and positioning of these dampers are obtained using the Globalized Bounded Nelder–Mead optimization method (GBNM). This method requires no gradient and is proved to be capable of identifying the best feasible riser configurations according to a specific performance criteria. A case study addresses the operational viability of the catenary riser with hydrodynamic dampers (CRHD) in an effort to reduce its material cost and improve its structural behavior. A nonlinear dynamic finite element analysis is necessary to evaluate the mechanical behavior of each candidate configuration, which makes the optimization process computationally expensive. As such, we discuss ways of improving the overall efficiency of the method by reducing the number of analyzed configurations.