Learning Forum

[Supreetha J]

Hello lior,

Gauge total pressure refers to the pressure value that you set at the inlet boundary condition relative to the atmospheric pressure. It is the total pressure minus the atmospheric pressure. In Ansys Fluent, when you are setting up a pressure inlet boundary condition, you would enter the gauge total pressure value that you want to simulate. 
The initial gauge pressure is used in cases where you are dealing with supersonic flows. It represents the initial condition of the pressure at the inlet, which is used by the solver during the initialization of the simulation.

Thank you.