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 (C Lrms) with reduced wind velocity has been studied.