When I run my model in CFX-solver, I saw the followering notice:

" A wall has been placed at portion(s) of an outlet boundary condition ( at 39.3 % of the faces, 38 % of the area) to prevent fluid flowing into the domain. The boundary condition name is outlet1. the fluid name is air at 25℃. If this situation persists, consider switching to an opening type boundary condition instead. "

------------------------------------------------------ Could you give me some advice to solve my case.

The model is simple: a cuboid with two open end as outlet 1 and outlet 2, a hole in another surface is a inlet.

I use Extrude to creat the cuboid and the inlet hole(a little cylinder)

It means that the outlet is placed near an area of re-circulation. Either the flow from the INlet is not fast neough to reach the outlets or they are located in regions hwree the flow may be re-circulating. To avoid this you can use an Opening instaed of an outlet