While setting boundary conditions for a pressure inlet (using ANSYS Fluent) values for Total Gauge Pressure and Supersonic/Initial Gauge Pressure required.
Although Ansys clearly defines Gauge, Static, Dynamic and Total Pressure, concepts like Total Gauge Pressure and Supersonic/Initial Gauge Pressure seem a bit confusing.
1) What is the difference between those values and what is their physical meaning?
2) How do we relate those concepts with the concept of Operating Pressure and could they be interchangeable? For example, setting Operating Pressure to be 0 and adding a Gauge Pressure equal to the Operating Pressure (atmospheric pressure). What would it change?
What I know to be true about Fluent solver is, you need to know the definition of Total, operating, and gauge pressure.
You can find the, in the help. If you add operating pressure and gauge pressure you should get the absolute pressure.
Dynamic pressure is due to velocity. Static is the one which can be measured using static pressure sensors, those holes on pitot tube's sides. (Look at airplane pressure and velocity sensors structure).
Initial gauge pressure helps the solver to converge to the solution faster and more precise. You just give the solver the interval or range which it should find the pressure. if you don't put it right, the solver will try to find it and it takes time and money and may bring some error and instability (based on your solver type) to your solution.
What I know to be true about Fluent solver is, you need to know the definition of Total, operating, and gauge pressure.
You can find the, in the help. If you add operating pressure and gauge pressure you should get the absolute pressure.
Dynamic pressure is due to velocity. Static is the one which can be measured using static pressure sensors, those holes on pitot tube's sides. (Look at airplane pressure and velocity sensors structure).
Initial gauge pressure helps the solver to converge to the solution faster and more precise. You just give the solver the interval or range which it should find the pressure. if you don't put it right, the solver will try to find it and it takes time and money and may bring some error and instability (based on your solver type) to your solution.
I'm agree with you but still doubt is not clear. Suppose for NPR 4 I've set Gauge Total pressure at Inlet = 405300 Pa
Gauge pressure at outlet = 0 Pa
What will be the Supersonic/initial gauge pressure at inlet ?
To Bholu, like Fariborz said in the end, the supersonic/initial gauge pressure is specified to get a faster convergence and stable calculations.
This value is predicted according to estimating the inlet velocity (incompressible) or the inlet Mach No. (compressible). If your case is super-sonic at inlet, this value must be specified. Otherwise, it'll be ignored by Fluent in subsonic case.
Entering a certain value in supersonic/initial... less than the total pressure value, Fluent will calculate inlet initial velocity based on Bernoulli's equation (incompressible) or isentropic relation (compressible) in initialization.
You can try 405000 Pa, 404500 Pa, 404000 Pa... of supersonic/initial...and see the computing time of same total steps.
You can check this link :
http://www.cfd-online.com/Forums/fluent/32708-pressure-outlet-back-flow.html
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