Simulation of vortex core precession in a reverse‐flow cyclone

A large‐eddy simulation of the single‐phase turbulent flow in a model cyclone geometry on a uniform, cubic computational grid consisting of 4.9×10 6 cells was performed. The Navier‐Stokes equations were discretized according to a lattice‐Boltzmann scheme. The Reynolds number, based on the inlet velocity and the cyclone body diameter, was 14,000. A standard Smagorinsky subgrid‐scale model with c s = 0.1, including wall‐damping functions, was applied. The 3‐D, average flow field was predicted with a high level of accuracy. Furthermore, the simulations exhibit vortex‐core precession, that is, the core of the main vortex is observed to move about the geometrical axis of the cyclone in a quasi‐periodic manner. The Strouhal number associated with the simulated vortex‐core precession was 0.53, whereas 0.49 was experimentally observed in a similar geometry at approximately the same Reynolds number.