what is the difference between PRESSURE_FARFIELD boundary condition and PRESSURE_OUTLET with pressure defined at infinity- boundary condition ? y should i define the gas as "ideal gas" if i have t use PRESSURE FARFIELD boundary condition ???

pressure far field is applied when u r using a large domain around the body like a wing or a blade/airfoil.. pressure outlet is prescribed at the outlet boundary where flow is taking . for far field B.C we use ideal gas b coz it is used for compressible flows for flow arond airplane wing.. like that.