Hello,
First thing, be aware that you have selected convection under thermal condition. This signifies that there is convection on the outer side of the pipe wall, and it is not for inside. Moreover, you have set the heat transfer coeff. to 0 which I think won't make any sence here. If you want to give constant temperature, select temperature under thermal condition and set appropriate value. Once the simulation is over, you can use report definitions to find out outlet temperature.
For details, check this course on heat transfer on our AIC site: Heat Transfer Modeling in Ansys Fluent | Ansys Courses
Thank you!
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