Create: Particles

Particles are discrete objects with individual trajectories governed by Newton’s second law. Each particle is characterized by a set of kinematic properties (position, velocity, acceleration, etc.) and physical properties (density, size, composition, etc.). Particle motion follows a Lagrangian specification (unlike fluid motion which uses the Eulerian concept of a field/lattice). As such, particles can assume arbitrary positions and velocities across the simulation domain as they evolve through space and time.

Every particle is a member of a particle family, which is characterized by a parent-child relationship. The parent defines the overall properties of the particle set, such as the density, size distribution, forces, breakup/coalescence mechanics, and scalar-coupling. The parent also defines how particles are added to the system. Children geometry define the shape, geometry, and extent of any localized particle addition.

Particle Types

• Massless Tracers: Massless tracer particles have no inertia, follow the fluid streamlines, and are one-way coupled to the fluid. They are useful for visualizing flow and predicting residence times.

• Inertial Particles: Inertial particles have a specified density and diameter. They are useful for modeling solid particle suspension, particle settling, liquid-liquid dispersions, and liquid-particle reactions.

• DEM Particles: DEM or discrete element particles extend the functionality of inertial particles to include particle-particle contact mechanics. They are useful for modeling slurries, granular flows, and particle packing problems.

• Liquid Droplets: Liquid droplets are used to model immiscible two fluid–dispersion processes. These droplets can be two-way coupled to the fluid and support particle-particle interactions.

• Gas Bubbles: Gas bubbles are low-density inertial particles which support breakup, coalescense, and interfacial gas-liquid mass transfer. They are used to model sparged gas systems and air lift reactors; they also predict gas holdup and gas drawdown processes via Lagrangian-Eularian coupling.

Adding Particles

• Injection Options: Both the number and the location of particles must be considered.

• Particle size distribution: There are six options for initial particle diameter distribution.

• Advanced Particle Injections: Customize the particle injection location, rate, size, and composition.

Particle Dynamics

• Forces and Fluid Coupling: Particle trajectories are governed by Newton’s second law.

• Breakup and Coalescence: Typically occurs on the level of individual particles and is informed by both physical and kinematic properties.

• Scalar Coupling and Thermal Coupling: Species or energy can be exchanged between particles and an associated field.

Particle Theory

• Nearest Neighbor Distribution: Predicts particle dispersion characteristics and compares results to first principle expectations.

• DEM Particle Interactions with Solid and Static Bodies: DEM particles require user-defined models for describing interactions with solid surfaces and other DEM particles.

• Webinars: Check out our webinars on particle theory.