Large Eddy Simulation of CSTR Systems: Comparison to Theory and Experiment

The mixing properties of CSTR systems are predicted using fully transient large-eddy lattice-Boltzmann simulations.  By adding massless tracer particles to the tank inlet, the spatiotemporal variation in the mean-age of the fluid and the local fluid residence time can be calculated on-the-fly throughout the course of the simulation.  In addition to identifying the mixing behavior of well-stirred systems, this modeling approach can be used to predict the behavior of imperfect CSTR systems, wherein some portion of the particles leave the system prematurely.  Predictions from these simulations are compared to predictions from analytical models and to experimental data.  Recommended relationships between grid resolution, tracer particle concentration, and simulation runtime are presented.  The extensibility of this approach to study tracer particles with mass (and inertia), along with its ability to predict local eddy dissipation rates and transient impeller blade forces is also discussed.