Multi-scale simulation of two-phase flows in energy systems

Abstract

A numerical analysis of the internal flows is performed to im- prove the current understanding and modelling capabilities of the complex flow characteristics encountered in energy systems. Simulation is divided into two stages, micro- and macro-scales. The averaged Navier–Stokes equations are solved numerically for the gas phase. The particulate phase is simulated through a Lagrangian deterministic and stochastic tracking models to pro- vide particle trajectories. The particles are assumed to interact with a succession of turbulence eddies, as they move through the computational domain. The results obtained highlight the cru- cial significance of the particle dispersion in turbulent flow and high potential of statistical methods. Strong coupling between acoustic oscillations, vortical motion, turbulent fluctuations and particle dynamics is observed. Acoustic oscillations provide ad- ditional mechanism to transfer energy from periodic motions to turbulence leading to an enhanced level of turbulence intensity. Acoustic waves give rise to an early transition from laminar to turbulent flow through energy transfer from the organized oscil- latory field to the broadband turbulent flowfield.