Rob
Ansys Employee

Boolean is a CAD operation to create the bodies. However, in CAD we don't consider surface connectivity. Share Topology is the the modelling step to tell the geometry that the two (or more) coincident faces are connected and therefore flow/heat/stuff should be passed across the surface. Alternatively an non-conformal interface is created which sort of does the same thing but is computationally less efficient: we use them when they're needed but they're not needed here.