TY - GEN

T1 - Development and validation of passive yaw in the open-source wec-sim code

AU - Forbush, Dominic D.

AU - Ruehl, Kelley

AU - Ogden, David

AU - Van Rij, Jennifer

AU - Yu, Yi Hsiang

AU - Tom, Nathan

N1 - Publisher Copyright:
© 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

PY - 2020/12

Y1 - 2020/12

N2 - A passive yaw implementation is developed, validated, and explored for the WEC-Sim, an open-source wave energy converter modeling tool that works within MATLAB/Simulink. The Reference Model 5 (RM5) is selected for this investigation, and a WEC-Sim model of the device is modified to allow yaw motion. A boundary element method (BEM) code was used to calculate the excitation force coefficients for a range of wave headings. An algorithm was implemented in WEC-Sim to determine the equivalent wave heading from a body's instantaneous yaw angle and interpolate the appropriate excitation coefficients to ensure the correct time-domain excitation force. This approach is able to determine excitation force for a body undergoing large yaw displacement. For the mathematically simple case of regular wave excitation, the dynamic equation was integrated numerically and found to closely approximate the results from this implementation in WEC-Sim. A case study is presented for the same device in irregular waves. In this case, computation time is increased by 32x when this interpolation is performed at every time step. To reduce this expense, a threshold yaw displacement can be set to reduce the number of interpolations performed. A threshold of 0.01o was found to increase computation time by only 22x without significantly affecting time domain results. Similar amplitude spectra for yaw force and displacements are observed for all threshold values less than 1o, for which computation time is only increased by 2.2x.

AB - A passive yaw implementation is developed, validated, and explored for the WEC-Sim, an open-source wave energy converter modeling tool that works within MATLAB/Simulink. The Reference Model 5 (RM5) is selected for this investigation, and a WEC-Sim model of the device is modified to allow yaw motion. A boundary element method (BEM) code was used to calculate the excitation force coefficients for a range of wave headings. An algorithm was implemented in WEC-Sim to determine the equivalent wave heading from a body's instantaneous yaw angle and interpolate the appropriate excitation coefficients to ensure the correct time-domain excitation force. This approach is able to determine excitation force for a body undergoing large yaw displacement. For the mathematically simple case of regular wave excitation, the dynamic equation was integrated numerically and found to closely approximate the results from this implementation in WEC-Sim. A case study is presented for the same device in irregular waves. In this case, computation time is increased by 32x when this interpolation is performed at every time step. To reduce this expense, a threshold yaw displacement can be set to reduce the number of interpolations performed. A threshold of 0.01o was found to increase computation time by only 22x without significantly affecting time domain results. Similar amplitude spectra for yaw force and displacements are observed for all threshold values less than 1o, for which computation time is only increased by 2.2x.

UR - http://www.scopus.com/inward/record.url?scp=85099366356&partnerID=8YFLogxK

U2 - 10.1115/OMAE2020-19255

DO - 10.1115/OMAE2020-19255

M3 - Conference contribution

AN - SCOPUS:85099366356

T3 - Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE

BT - Ocean Renewable Energy

PB - American Society of Mechanical Engineers (ASME)

Y2 - 3 August 2020 through 7 August 2020

ER -