Single- and two-way coupled overset interpolations to model fluid-structure interactions of oscillating foils in OpenFOAM

Overset method is highly stable in modelling fluid-structure-interactions that involve large displacements of rigid or flexible oscillating bodies. However, the accuracy of these models can differ based on the coupling process of overset algorithms in the FSI numerical solvers. Here, we perform a comparative evaluation of a new in-house single-way coupling framework for the calculated velocity and pressure fields on overlapping grids, and an existing two-way coupled overset solver in OpenFOAM that is integrated with the fluid-solid interface modelling in solids4Foam. Preliminary benchmark results for the flow around Hron-Turek flexible beam suggests the presence of non-physical pressure oscillations by two-way coupling process. These, however, are not evident for our new single-way coupled framework. This hints at a better accuracy of our numerical technique in handling structural deformations, based on the imposed fluid forces. Currently, our efforts focus on assessing these techniques in analyzing the performance of rigid and flexible oscillating bluff bodies with prescribed motion, or free-swimming conditions, at moderate Reynolds numbers (1000≤Re≤4000). This will be expanded by wake dynamics assessment in order to fully validate the solver’s capabilities and accuracy.