STAR-CCM+’s Lagrangian multiphase model is the ideal tool for the study of the transport of a high number of dispersed particles such as liquid sprays.
Available for both steady state and transient solutions, the Lagrangian multiphase model has a number of supplementary models to enhance the accuracy and realism of the simulation. These models include: drag relationships, coulomb forces, mass transfer, particle chemical reactions and radiation, droplet breakup and atomization, collision and coalescence. As a particle impacts a wall, the user has control over its resultant behaviour - this includes interaction models such as Bai-Gosman as well as the formation of fluid films.
Discrete Element Method (DEM)
DEM can be used to simulate the motion of a large number of interacting discrete objects (particles), such as the granular flow of aggregates, food particles, metal powders, tablets and capsules, and wheat or grass. STAR-CCM+ was the first commercial engineering simulation tool to include a DEM capability that is fully coupled with numerical flow simulation in a single software environment.
DEM differs from Lagrangian multiphase in that it resolves the contact physics between particles for arbitrary particle shapes.
STAR-CCM+ is able to model basic spherical particles, or arbitrary composite or clumped particles which can take any shape and are formed from a number of primitive spherical particles. Composite particles are rigid, whereas clumped particles are deformable and breakable with the bonds between individual spheres modeled.
There are tools available to automatically generate composite particles from input CAD, for example from the scanned definition of a rock or the CAD definition of a tablet.
In common with Lagrangian multiphase, a number of models for the prediction of particle drag are available as well as particle heat transfer including inter-particle conduction.
For simulations involving very large numbers of particles, such as fluidized beds, STAR-CCM+ has the DEM Coarse Grain Particle Model. This model allows large numbers of fine scale particles to be represented by a single larger coarse particle (parcel), the fluid-particle dynamics is then calculated on the fine scale particles, and the contact dynamics such as collisions are calculated on the coarse scale parcels. This option can substantially reduce the computational expense of using the DEM model for simulating large numbers of particles.