Towards the Development of an Ocean Engineering Library for OpenModelica

Abstract

The development of component models to populate a proposed OpenModelica standard library for the ocean engineering domain is described through the process of modelling the response of catenary-moored wave-energy converters in the ‘free-to-use’ OpenModelica simulation environment and its associated OMEdit graphical user interface. A wave energy conversion concept is presented, followed by the implementation of Modelica component models and functions to simulate wave, current, and mooring loads on a cylindrical floating object. The irregular sea surface is specified using the Pierson-Moskowitz spectrum and the heave force on the buoy is determined based on the Froude-Krylov formulation. Mooring load formulation is based on the catenary theory. Combined wave and current loads on the buoy and on the mooring chain are arrived at using the Morison equation. The results are verified with the commercial software Orcaflex, and the preliminary OceanEngineering library is made available for download. The integrated simulation of the multiphysical wave energy buoy system is then carried out to determine the energy harvest potential, and results discussed. An alternative design is then suggested and simulated to demonstrate the advantages of using the component-based approach.