[modest_may]

I am using the ansys-fluent adjoint solver module to optimize a pipe channel. When the primary flow solution is finished, the mass-weighted average total pressure over the inlet (Pt_in_p) is 150000.0Pa. However, when i create a surface-integral observables in the adjoint module, the mass-weighted average total pressure over the inlet (Pt_in_a) is 148000.0Pa. Why is the Pt_in_p not equal to Pt_in_a?

I sincerely hope someone could give me some tips, thanks !