Flow around objects of various shapes, including circular cylinders, are central to many industrial applications. Reliable simulation of such flows remains a significant challenge. We describe such challenges and related numerical issues that have been recently addressed. In many cases, the relevant flow patterns are chaotic. We explore methods for evaluating the coherence of lift and drag forces for chaotic flow around a cylinder. We utilize a method based on assessing the proclivity for resonance in the oscillations of the cylinder. We compare the resonance approach with Fourier analysis of the lift force.