In Ansys Discovery 2024R2, if you want to show fluid-to-fluid interfaces it can be activated from Settings >> Physics >> Workflow options >> Show fluid-to-fluid interfaces. You need to restart Discovery to see the changes.

Show fluid-to-fluid interfaces was released as Beta Feature in Ansys Discovery 2024R1 and you could activate it from the Advanced options under Settings and you should restart Discovery to see the effect. You can refer to this to Ansys Discovery: Activating Beta Feature – Ansys Knowledge for more information on how to activate the beta feature.

Once you activate Show fluid-to-fluid interfaces it gives you control over the detection distance and helps in visual diagnosis of the overlapping faces.

You can decrease the detection distance to find small gaps between close fluid regions. These gaps can then be resolved to generate fluid-fluid interfaces.

You can refer to the attached pdf Fluid Interfaces