Forced oscillations of a rigid cylinder in viscoelastic fluid flow

We investigate the effects of fluid elasticity on the flow forces and the wake structure when a rigid cylinder is forced to oscillate sinusoidally in a viscoelastic fluid flow. A two-dimensional, uniform, incompressible flow of viscoelastic fluid is considered at Re=100. The FENE-P model is used to model the viscoelastic fluid. We study how the flow forces and the wake patterns change as the reduced velocity, U^*, Weissenberg number, Wi, oscillation amplitude, A^*, and the maximum polymer extensibility, L², change. We analyze the flow forces in the frequency domain to determine the lock-in range in terms of Wi at a constant U^*. The average power is calculated to determine the range of Wi, where self-excited oscillations might occur if the cylinder is allowed to oscillate. We also investigate the effect of fluid elasticity on the added mass coefficient at a constant reduced velocity. For a constant Wi, the strength of the elastic stresses increases, and the strength of vortices reduces with increasing reduced velocity.