manu prabha anand

yes, I have read it before. 

"The static pressure (termed the Supersonic/Initial Gauge Pressure) must be specified if the inlet flow is supersonic or if you plan to initialize the solution based on the pressure inlet boundary conditions. 

The Supersonic/Initial Gauge Pressure is ignored by ANSYS FLUENT whenever the flow is subsonic. If you choose to initialize the flow based on the mass flow inlet conditions, the Supersonic/Initial Gauge Pressure will be used in conjunction with the specified stagnation quantities to compute initial values according to isentropic relations."

My question is if i know a gas flow mas flow rate, in which the pressure of the gas is 9 bar, how to fix mas flow rate and pressure at the inlet. I have given 9 bar supersonic gauge for initialization, but i had calculated density for 9 bar using (rho=P/RT) and given the density to the fluid medium constant. " if i give density constant to fix the pressure of the flowing fluid. what is the error in my input? Am