Built-in auxiliary dependent variables for the mass and temperature can be activated by selecting the Compute particle mass and Compute particle temperature check boxes, respectively, in the Additional Variables section of the Settings window for the physics interface. When the option to compute particle mass is activated, it is possible to set the initial particle mass in particle release features, such as Release, Inlet, and Release from Grid. It is also possible to select a distribution function for the initial mass or diameter. This is important when modeling separation devices where the goal is to understand the transmission probability of particles of various sizes.
When solving for particle diameter or mass, particles may increase or decrease in size over the duration of the transient analysis. In particular, if the particles represent liquid droplets in a gas, the built-in Droplet Evaporation node can model their gradual reduction in size.