Numerical simulation of lock-in effect of a 2-D rectangular section under forced oscillations

Abstract

Lock-in effect of a 2-D rigid rectangular section with side ratio (B/D; B is the dimension along the flow direction and D is the dimension normal to the flow direction) of 2 has been numerically simulated by subjecting it to forced sinusoidal oscillation with an amplitude of 0.1 D in transverse direction. Dynamic mesh, which deforms in accordance with the motion of the rectangular section, has been used to model a portion of computational domain around the rectangular section. Simulations have been carried out for a reduced velocity range of 5 to 25 using two popular Reynolds Averaged Navier-Stokes (RANS) based turbulence models, viz, Realizable k-ε model (RKE) and Shear Stress Transport k-ω model (SST) in commercial Computational Fluid Dynamics code FLUENT. The range of reduced wind velocities for which the rectangular section is in lock-in has been evaluated to be between 6 and 17 from RKE model, while from SST model, the range has been observed to be 6 to 18. This has been compared with the experimental results reported in literature. Further, the variation of root mean square value of lift coefficient (CLrms) with reduced wind velocity has been studied.