## 31.3. Particle User Routines

Particle user routines are used to create user defined injection regions and particle user sources. Creating a user routine with the `Particle User Routine` option selected is identical to creating a routine with the `User CEL Function` option selected. For details, see:

- User CEL Routines

- Particle Injection Regions Tab

- Particle User Sources in the CFX-Solver Modeling Guide.

Release 18.2 - © ANSYS, Inc. All rights reserved.