Anyone can explain what is wrong with mesh setup ?
external stl files used. simple water jacket model
test_2024-05-30T115055.132221.zip (1.8 MB)
You will get better mesh if you don’t use stl files for the inlet and outlet. Just extend the cylinders so they stick out of the x=xmin plane. Then define rectangular BC regions around the inlet and outlet. Only the fluild cells belonging to the inlet/outlet will be used.