(663f) Coupled CFD-DEM Simulations for Heat-Exchanger Cleaning

Particle transport in a plate-type heat exchanger having tortuous paths is a ubiquitous topic chemical/environmental engineering. Sub-micron particles experience various types of interactions such as electrostatic interactions, Brownian random forces/torques, gravitational/buoyant forces, and more importantly hydrodynamic forces/torques due to the ambient (often linear shear) flow field. The recent interest of particle science pays more attention to inelastic granules or granular materials, having sizes of at least 100 micrometers. Collision dynamics of these large, inelastic particles in thin flow channels have great importance in process engineering. We use a large-scale, parallel computation dealing with particles of an order of O(10^3) to track all the particles' linear and angular motion at each time step. Fluid fields inside the thin slits are solved using an open-source CFD package, OpenFOAM, in parallel, and simulation results such as velocity, vorticity, and rate of strain are imported to mimic the particle motion. Dynamics of particle-particle and particle-wall collisions are accurately simulated using the dissipative hydrodynamics (DHD) (as a general version of Stokesian dynamics), which can cover frictional interactions and inelastic collisions between two unequal-sized particles. We currently focus on the application of DHD for granular dynamics in confined spaces, including thin or curved flow channels. The fundamental insight of hydrodynamic transport of inelastic granules will provide a deep understanding of the transport of inelastic granules in geometrically confined flow channels.