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.

Modelica Component Models for Oceanic Surface Waves andDepth Varying Current

“…For a better understanding of how these component models perform within an integrated simulation scenario, readers may refer to (Viswanathan and Holden, 2019). The present paper fills in for the lack of theoretical and implementational details for the wave and current component-models in the above work.…”

“…Theory and implementation of component-models for non-diffracting floating objects and for mooring forces based on the quasi-static catenary approach, used in (Viswanathan and Holden, 2019), is discussed in (Viswanathan and Holden, 2020), along with comparison of results for the same system modelled in the commonly used ocean-engineering software Orcaflex. Satisfactory agreement of surge/heave responses, and of Morison forces under various combinations of wave and current loading is demonstrated in (Viswanathan and Holden, 2020), and these maybe taken as proof for the correct representation of wave-current kinematics by the component models discussed in this work.…”

“…The advantages of developing an OpenModelica ocean engineering library populated with domain-specific component-models and functions to carry out the integrated simulation of multi-pyhsical ocean engineering systems was demonstrated by the authors (Viswanathan and Holden, 2019). This earlier work:…”

Simulating the Dynamics of a Chain Suspended Sub-sea Load Using Modified Components from the Modelica MultiBody Library

“…The authors discussed the benefits of developing a Modelica standard library for ocean-engineering applications in (Viswanathan and Holden, 2019). In the above work, the quasi-static approach was adopted to specify the mooring forces at any given simulation time-step.…”

Modelica Component Models for Non-diffracting Floating Objectsand Quasi-static Catenary Moorings

“…The advantages of developing an OpenModelica oceanengineering library populated with domain-specific component-models and functions to carry out the integrated simulation of multi-pyhsical ocean engineering systems was demonstrated by the authors (Viswanathan and Holden, 2019). This earlier work:…”