Abstract

The Ocean Engineering Toolbox (OET) is an open-source, Modelica™ compliant symbolic library capable of simulating the dynamic motions of floating bodies subject to polychromatic, unidirectional waves. This paper presents recent advancements in the OET: (1) the development of custom components to represent the frequency-dependent wave excitation force and (2) significant improvements in the toolbox’s computational performance. While the Modelica language can represent complex cyber-physical systems efficiently, the primary challenges with modeling wave-induced floating bodies are (1) non-compatibility with frequency-dependent variables, (2) lack of hydrodynamic components in the Modelica Standard Library (MSL), and (3) integration with the previous version of the OETv0.1. In the time-domain implementation, surface elevation profiles can now be generated for regular and irregular waves, with three spectral options for polychromatic seas: Pierson-Moskowitz (PM), Bretschneider, and Joint North Sea Wave Project (JONSWAP). Hydrodynamics coefficients are imported using a MATLAB script to process the output from Boundary Element Method (BEM) codes. A novel symbolic implementation of spectral decomposition and interpolation is presented in this work to generate the frequency-dependent excitation force in Modelica. Results from the OET are compared against data generated from WEC-Sim, validating both the wave excitation force and the corresponding system dynamic response for a floating point absorber in heave. These developments lead to superior simulation accuracy and computational performance while expanding the hydrodynamic modeling capabilities of Modelica.

This content is only available via PDF.
You do not currently have access to this content.