A computational-fluid-dynamics model for particle-size evolution in the presence of turbulent mixing

Abstract

A computational model for the simulation of the particle-size evolution of nanoparticles in mixing-controlled processes is presented. This model accounts for the effect of molecular mixing on particle-size evolution when mixing time scales are smaller than the phase-space time scales. The approach is formulated by deriving evolution equations for the moments of joint mixture fraction-size moments PDF, and closing such moment equations using the conditional quadrature method of moments. A test case consisting of a mixing-dependent aggregation problem in a multi-inlet vortex reactor is considered. The results accounting for the correlation between mixture fraction and size moments are compared against those computed neglecting such correlation to demonstrate its impact on the model predictions. The average particle volumes are different in the order of 104mm3 at the reactor exit under the studied conditions.