Nikhil Narale
Ansys Employee

If I'm understanding correctly, your goal is to facilitate the flow of fluid through the tunnel and then into the pipes, is that correct?

If so, here are the steps you can follow:

1: Ensure that you prepare the CAD appropriately in Ansys Discovery or Spaceclaim. This involves subtracting the pipe geometry from the tunnel geometry so that they become two separate bodies and do not overlap. Afterward, you can share the topology between the tunnel and the pipes. There will be 3 fluid cell zones in this case (1 tunner and 2 pipes)

2: If you are using Fluent Meshing Watertight workflow to create the mesh, it's important to convert all fluid-fluid boundary types from 'wall' to 'internal' when describing the geometry. This ensures that the fluid can flow seamlessly through different fluid cell zones.