I conducted fluid flow analysis on a heat exchanger and the boundary conditions were inlet acid at 65 degree C and water from a different inlet at 36 degree C but after running the simulation results showed that the inlet of acid was cold (blue) and the output was hot (red) while the water was cold from start to end.

expected results were the acid entering at 65 degree C was supposed to be cooled by the water which was at 36 degree C