[JulyJulyJuly]

Hi,
I am using ANSYS to simulate conjugate heat transfer conditions. Before starting on the real heat exchanger, I create a simple 3D model as a demo to practise meshing.
This 3D model contains 3 parts, the outer zone represents cold fluid which has 1 inlet and 1 outlet; The inner zone represents hot fluid which need to be cooled by cold flow; And between them is a U shaped metal pipe, conducting heat from the hot side to the cold side.
Here's the problem I encountered, as shown in the picture, I wanted to create inflation boundaries on both fluid zone surfaces, but however I assigned the Inflation control, there is no prisms on the cold fluid-pipe interface of the cold fluid zone.
As mentioned, I am modeling conjugate heat transfer, so I turn on the assembly meshing option even though I didn't know if it was related.
Would anyone help me solve this problem? It might be a simple issue but I do not know what to do, thanks a lot!

[JulyJulyJuly]

Another 2 pictures of my case.