This study investigates the unsteady gas flow structure in a cyclone separator using high-resolution Large Eddy Simulation (LES). Unlike traditional approaches, a method for analyzing velocity field dynamics based on velocity increments is proposed and validated. This technique enables the identification of coherent structures and high-frequency pulsations even on relatively coarse computational grids—a task beyond the capabilities of classical RANS models. Comparative analysis reveals that standard two-equation isotropic turbulence models systematically overestimate tangential velocity near the walls, suggesting they should be used with caution in cyclone applications. While the anisotropic RSM provides better agreement for the mean tangential velocity, it fails to capture the episodic “superbursts” and near-wall streaks resolved by LES. Numerical experiments revealed two distinct dynamic regimes in the conical section: continuous background pulsations caused by stochastic vortex migration and periodic superbursts triggered by vortex core–wall interactions. Special emphasis is placed on the identification of near-wall velocity streaks resulting from hydrodynamic instability in the viscous sublayer. It is shown that the unsteadiness and subsequent bursting of these structures induce high-frequency gas pulsations directly at the wall, which can significantly affect the dynamics of solid particles near the surfaces. These findings provide new insights into turbulent transport in swirling flows and establish a robust framework for further investigation of separation mechanisms.
Savin et al. (Wed,) studied this question.