(25c) Quantification of Gas–Phase Velocity Fluctuations In Statistically Homogeneous Gas–Solid Flow Using Particle–Resolved Direct Numerical Simulation
AIChE Annual Meeting
2011 Annual Meeting
Particle Technology Forum
Fundamentals of Fluidization I
Monday, October 17, 2011 - 9:10am to 9:30am
Gas–phase velocity fluctuations in statistically homogeneous gas–solids flow are quantified using particle–resolved direct numerical simulation (DNS). The kinetic energy associated with the gas–phase velocity fluctuations kf in steady flow past fixed random assemblies of monodisperse spheres is characterized as a function of solid volume fraction φ and the Reynolds number based on the mean slip velocity Rem. The DNS approach is based on a new formulation we refer to as the Particle–resolved Uncontaminated–fluid Reconcilable Immersed Boundary Method (PUReIBM). A simple scaling analysis is used to explain the dependence of kf on φ and Rem. The steady value of kf results from the balance between the source of kf due to interphase transfer of kinetic energy, and the dissipation of kf in the gas–phase. It is found that it is appropriate to model the dissipation of kf in gas–solid flows using a length scale that is analogous to the Taylor microscale used in single–phase turbulence.