Wake Dynamics of Bio-Inspired Cylinders Using a Lattice Boltzmann–Immersed Boundary Approach
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Fluid–structure interaction problems involves many engineering applications. In civil engineering, a particularly critical issue is the erosion phenomena which requires careful investigation, indeed it develops around bridge pylons or offshore wind farms [1, 2, 3]. Essential is the accurate characterization of the hydrodynamic loads on the pylons such as the vortex formation. This work investigates the low-Reynolds number flow past bio-inspired cylinders as potential alternatives to conventional circular pylons. The numerical methodology based on the coupling between the Lattice Boltzmann Method and the Immersed Boundary Method is employed. Within this framework a Large Eddy Simulation approach based on the Smagorinsky subgrid-scale model is employed [4]. Simulations have been performed by a multi-grid approach providing the high resolution required to capture the near-wall flow characteristics while reducing the memory requirements. The investigation focuses on the characterization of the downstream wake at low-Reynolds numbers, with particular emphasis on the coherent and transitional flow structures generated by the vortex-shedding process. Special attention is devoted to the evaluation of hydrodynamic forces, namely drag and lift, and to their correlation with wake dynamics. The study is further extended to the vibrating case in order to examine the influence of bio-inspired geometries on vortex-induced vibrations in the low-Reynolds-number regime. In the static case, the results are subsequently validated by comparing the velocity fields and wake topology with planar Particle Image Velocimetry (PIV) measurements in water flow.
