The absolute nodal coordinate formulation in the analysis of offshore floating operations, Part II: Code validation and case study

Abstract

The absolute nodal coordinate formulation (ANCF) proposed in Part I of this paper series is applied to simulate flexible structures in the offshore operation analysis. The Part II of this paper series aims to validate the in-house code MiNos developed based on ANCF, a module of software KraKen, and employ the code to the static and dynamic analysis in time domain for flexible cables and mooring lines in actual operation scenarios. Three validation cases are conducted to demonstrate the accuracy and robustness of the in-house program for time domain analysis of arbitrary large deformation flexible structures. Furthermore, various floating operations, including crude export, production riser operation, and emergency disconnection of a turret are simulated by MiNos for both static and dynamic analysis, the results of the flexible cables and lines in these cases are compared with commercial software OrcaFlex. The high continuity of ANCF elements ensures high accuracy in the analysis of floating operation which comprises sophisticated vessel motions, wave loads, and soil contact. Besides, the inherent numerical problems of nonlinear dynamic analysis such as non-physics oscillations and peaks can be mitigated by ANCF. Therefore, ANCF could be considered as a promising theory for the dynamic analysis of flexible structure of cables and lines in marine operations.