Errors and Uncertainties in Simulation of Unsteady Viscous Flow Over a Circular Cylinder at Re = 48

The flow past a circular cylinder is an important problem of investigation in applications such as structural engineering (bridge structures, tall buildings, chimneys, etc.) and aeronautical engineering (bluff body aerodynamics). CFD based on the Finite Volume Method implemented in the solver Fluent shows that aerodynamic coefficients while predicted with remarkable accuracy for the two-dimensional, steady, viscous flow past a circular cylinder case revealed errors or discrepancies in the prediction of von Kármán vortex street (and associated periodicity of lift and drag) at the Reynolds number range of 46–48. The reason for the discrepancy is investigated with a focus on predicting von Kármán vortex street at Re of 48, by making different grid design considerations, viz., varying the blockage ratio, upstream distance of cylinder to inlet, downstream distance from cylinder to outlet boundary and mesh element size parameter. Although the known flow characteristics such as fluidic unsteadiness, force oscillations and vortex shedding predictions existent at this Re were never predicted, the mean drag coefficient was predicted in all cases with high degree of accuracy. The recommendations and conclusions drawn from the study could now be applied to different fluid flow problems. The earlier obtained results provided guidance on how to find solutions to different applications as well as perform more complex fluid flow simulations effectively, with minimal error and effort.