Abstract
With the continued upscaling of marine hydrokinetic (MHK) turbines, there is need for the development of more accurate fluid-structure interaction (FSI) capabilities to handle the increased deflections and stresses associated with larger turbines. This paper will present the results acquired from opensource software used to compare two FSI coupling strategies—one-way FSI and strongly coupled two-way FSI. The fluid solver and solid solver are OpenFOAM v7 [1] and CalculiX [2] respectively, and both are coupled using the preCICE [3] (Precise Code Interaction Coupling Environment) coupling library. While one-way FSI can be appropriate for modelling deflections in rotating machinery, such as axial flow turbines and propellers, in some case it has been found to be inadequate in describing the highly cyclical deflections and stresses exhibited by large, crossflow turbines. This is likely due to one-way FSI not describing how geometry deformation effects the flow field. Two-way FSI can capture these effects but with a higher computational cost. This paper compares both FSI methodologies and analyses the results when both are implemented for a simply supported, twisted hydrofoil. Specifically, an investigation is carried out to determine how much stresses and displacements are underestimated by one-way FSI and if fast processing time is worth the potential inaccuracy. The investigation reveals that there is an increase in stress, displacement, lift, and drag when two-way modelling is used. The results confirm that there is a modest change in the physical metrics of stress and displacement, as well as noteworthy changes in the performance metrics—lift and drag. The investigation concludes with the determination that two-way FSI is worth the computational cost and that further work for a rotating geometry is warranted.1