Correlation of the Surface Pressure Distribution on a Circular Cylinder with Objective Identification of Vortex Formation and Shedding

Numerical simulation of the unsteady wake downstream of a circular cylinder was studied by comparing the cylinder static pressure distribution and the results from a Lagrangian finite-time Lyapunov exponent (FTLE) analysis. The location and evolution of Lagrangian saddle points found using FTLE in the flow were tracked to facilitate the understanding of vortex shedding physics in the near-wake region, and their motion was compared with the simultaneous static pressure distribution on the cylinder surface. Relating the Lagrangian saddle dynamics to a quantity that is measurable in real-time allows for sensing of the Lagrangian saddle point location. The Lagrangian saddle point acceleration away from the cylinder surface was found to coincide with the increase of the static pressure at 100◦ from the mean cylinder stagnation point.