UDM Parameters

UDM geometry can be manipulated through its parameters:

View of the Parameters tab for a UDM

These parameters

UDM geometry in HFSS invoked through Workbench is not 'dynamically updated' upon parameter edits.

The UDM shows a lightning bolt icon by the model name when parameters are edited.

Lightning bolt icon next to model name.

You must run the Send Parameters and Generate command to synchronize parameters with geometry.