Python-based lattice Boltzmann method simulation of the von Kármán vortex street behind a cylinder & comparison with PIV

A Python-based lattice Boltzmann method (LBM) simulation of the von Kármán vortex street behind a circular cylinder at a moderate Reynolds number (Re = 150) has been developed with validation through particle image velocimetry (PIV) experiments and historical experiments conducted by experts in the field. The LBM implementation uses the D2Q9 lattice, BGK collision model, and Zou/He boundary conditions for inflow and outflow. Simulated velocity and vorticity fields are compared with PIV data collected in a recirculating water tunnel. Aside from qualitative similarity, the dominant vortex shedding frequency extracted from velocity probes is in good quantitative agreement with theoretical Strouhal number predictions, yielding a Strouhal number of 0.187 — around 1% error from the experimentally determined value of 0.185. This agreement validates the accuracy of the solver and highlights LBM’s potential as a flexible, accessible CFD tool for undergraduate fluid dynamics education and unlocks a potentially invaluable tool in fluids research at the University of North Carolina at Chapel Hill.