When performing simulations, it is often useful to reduce the complexity of a model to save on computational resources and time. When a model can be defined by repeating patterns, it is possible to use the concept of periodicity and analyze only one of the patterns instead of the full model. In this lesson we will discuss the different types of periodicities, how they are used in simulations, and why it is important to account for them at the meshing stage. We will learn about the advantages of meshing periodic boundaries with the Ansys Fluent Meshing Watertight Geometry Workflow and when the automatic and manual methods should be used. We will also explore how to extract the necessary periodicity inputs from the geometry using Ansys SpaceClaim when the manual meshing method must be used.