The unified topology layer (UTL) is only available for the Watertight Geometry meshing workflow.

The primary difference between the UTL version of the workflow and the non-UTL version is the addition of the topology option for tasks involving selecting portions of the CAD.

Use the topology option to ensure that selections you define in meshing are carried into the solver. Refer to Using the Watertight Geometry Meshing Guided Workflows in the Fluent User's Guide for additional information on using the workflow.