Partitioned iterative and dynamic subgrid-scale methods for freely vibrating square-section structures at subcritical Reynolds number

In this paper, we present a partitioned iterative and a dynamic subgrid-scale (SGS) scheme to simulate flow-induced vibration of freely vibrating structures in a turbulent flow. The hybrid partitioned scheme relies on the combined interface boundary conditions and non-linear interface force corrections to stabilize the variational coupled system based on the filtered Navier-Stokes and rigid-body dynamics. The iterative interface corrections provide the force equilibrium with arbitrary accuracy while maintaining the velocity continuity condition along the fluid-structure interface. We show that our second-order scheme is stable for both VIV and galloping instabilities found in a freely vibrating square cylinder with strong added-mass effects for mass ratio (solid mass to displaced fluid mass) ranging from m* ∈ [0.1, 10]. We validate the dynamic subgrid-scale scheme for the benchmark problem of the three-dimensional (3D) flow past a square cylinder at moderate Reynolds number. We assess the response characteristics of freely vibrating square cylinder with the recent experimental data at zero and 45o incidence. We demonstrate the SGS-based large-eddy simulation solver for full-scale multicolumn semi-submersible floater subjected to flow-induced motions at subcritical Reynolds number Re=20,000 based on the diameter of column section. The transverse amplitude and the Strouhal number of the floater are validated against the experimental data.