Modeling steady-state and transient forces on a cylinder

Numerical simulations of the flow past a stationary circular cylinder at different Reynolds numbers (Re) have been performed using a computational fluid dynamics (CFD) solver that is based on the unsteady Reynolds-averaged Navier-Stokes equations (RANS). The results obtained are used to develop reduced-order models for the lift and drag coefficients. The models not only match the numerical simulation results in the time domain, but also in the spectral domain. They capture the steady-state region with excellent accuracy. Further, the models are verified by comparing their results in the transient region with their counterparts from the CFD simulations and very good agreement is found. The work performed here is a step towards building models for vortex-induced vibrations (VIV) encountered in risers, spars, and other offshore structures.