Meaning
Multiphase flow simulation methods solve the equations of motion for a continuous fluid phase alongside a dispersed secondary phase. The discrete phase model tracks individual particles, bubbles, or droplets through a pre-calculated continuous flow field. This approach computes the trajectories of these discrete entities by balancing the forces acting on each particle, including drag, gravity, and virtual mass.
It applies primarily to flows where the volume fraction of the dispersed phase remains low enough to avoid extensive particle-to-particle collisions.
Eulerian Lagrangian Frame
The continuous fluid is modeled using the Eulerian framework, while the discrete phase uses the Lagrangian formulation to track individual trajectories. This dual-frame approach calculates the transfer of momentum, heat, chemical species, and mass between the fluid and the particles. It allows detailed modeling of spray drying, fuel injection, dust collection, and aerosol transport.
Particle Tracking
Equations of motion are integrated over discrete time steps to predict the position and velocity of each particle. The model accounts for turbulent dispersion by applying random walk methods that simulate the effect of fluid eddies on particle paths. This tracking helps engineers predict erosion patterns and deposition rates on solid walls.
Computational Constraint
High volume fractions of the dispersed phase violate the assumptions of the model, which requires more complex Eulerian-Eulerian formulations. Tracking millions of individual particles also demands substantial memory and processing power, limiting its use in dense fluidized beds.
