Learning Forum

[Jason Sum]

My project aims to simulate pumping pressurized air into the U shape pipe, to pump away the water remaining inside the pipe.nSay now I want to set the inlet gauge pressure of gas being pumped in to be 20 psi nIf I want the inlet gas pressure initially reached 20 psi and keep 20 psi constantly pumped, should I set both Total Gauge Pressure & Supersonic/Initial Gauge Pressure to be 20 psi?nOtherwise, if I want the inlet gas pressure increase from 0 gauge pressure to 20 psi, should I set Supersonic/Initial Gauge Pressure to be 0 psi and set Total Gauge Pressure to be 20 psi? nThanks for helping me!n

[Rob]

The supersonic part only matters if the flow is supersonic, is it? n

[Jason Sum]

I am not sure the flow is supersonic in the inlet, should I input a value close to that of Total Gauge Pressure into Supersonic/Initial Gauge Pressure ? nI found online that Supersonic/Initial Gauge Pressure is predicted according to estimating the inlet velocity (incompressible) or the inlet Mach No. (compressible). If the case is super-sonic at inlet, this value must be specified. Otherwise, it'll be ignored by Fluent in subsonic case. nCan I type both Total Gauge Pressure and Supersonic/Initial Gauge Pressure with same /similar values in case I am not sure the flow is supersonic or subsonic?nThanks so much for answering!n

[Rob]

You can, but it's always recommended to understand the flow field you are modelling to ensure you are using the correct models. n