Browsing by Author "Yim, Solomon C."

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    Numerical and Experimental Analysis of the Ocean Sentinel Mooring System to Enable Improved Modeling and Design
    von Jouanne, Annette; Baker, Josh; Yim, Solomon C.; Amon, Ean; Moran, Sean; Lettenmaier, Terry (2014-04)
    This paper presents the design and analysis of the Ocean Sentinel instrumentation buoy mooring system, including numerical modeling and experimental validation testing during the summer of 2013. The intent of this study is to gather mooring data for the Pacific Marine Energy Center – North Energy Test Site (PMEC-NETS), and increase the understanding of numerical mooring models, which will contribute to improved designs of wave energy converter (WEC) mooring systems. The Ocean Sentinel instrumentation buoy (Ocean Sentinel) was configured in a three-point moor, with load cells on each mooring line, and the system was modeled using OrcaFlex. The model predictions of the mooring line loads are compared with actual experimental loads experienced during the summer 2013 deployment and the results are presented. Based on the results of the field testing, mooring system design improvements are proposed. This paper also includes wave data recorded during the deployment that was used in the numerical model to simulate the deployed conditions, as well as the simulated power output for a WEC array installation located at PMEC-NETS.
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    Numerical Simulation of the Fluid-Structure Interaction of a Surface Effect Ship Bow Seal
    Bloxom, Andrew Lawrence (Virginia Tech, 2014-10-22)
    Numerical simulations of fluid-structure interaction (FSI) problems were performed in an effort to verify and validate a commercially available FSI tool. This tool uses an iterative partitioned coupling scheme between CD-adapco's STAR-CCM+ finite volume fluid solver and Simulia's Abaqus finite element structural solver to simulate the FSI response of a system. Preliminary verification and validation work (VandV) was carried out to understand the numerical behavior of the codes individually and together as a FSI tool. Verification and Validation work that was completed included code order verification of the respective fluid and structural solvers with Couette-Pouiselle flow and Euler-Bernoulli beam theory. These results confirmed the 2nd order accuracy of the spatial discretizations used. Following that, a mixture of solution verifications and model calibrations was performed with the inclusion of the physics models implemented in the solution of the FSI problems. Solution verifications were completed for fluid and structural stand-alone models as well as for the coupled FSI solutions. These results re-confirmed the spatial order of accuracy but for more complex flows and physics models as well as the order of accuracy of the temporal discretizations. In lieu of a good material definition, model calibration is performed to reproduce the experimental results. This work used model calibration for both instances of hyperelastic materials which were presented in the literature as validation cases because these materials were defined as linear elastic. Calibrated, three dimensional models of the bow seal on the University of Michigan bow seal test platform showed the ability to reproduce the experimental results qualitatively through averaging of the forces and seal displacements. These simulations represent the only current 3D results for this case. One significant result of this study is the ability to visualize the flow around the seal and to directly measure the seal resistances at varying cushion pressures, seal immersions, forward speeds, and different seal materials. SES design analysis could greatly benefit from the inclusion of flexible seals in simulations, and this work is a positive step in that direction. In future work, the inclusion of more complex seal geometries and contact will further enhance the capability of this tool.