Simscape Fluids Simple Pressure Drop Error

Simscape Fluids produces an error when simulating a very simple gas network which I have shown below. The idea is to observe the pressure at port B of the valve (variable orifice) with a constant upstream pressure and mass flow rate. I would appreciate any help trying to resolve this problem.

Reservoir (G) Pressure: 350 psi

Reservoir (G) Temp: 50 degF

Mass Flow Rate: 0.176 kg/s

Reservoir (G)1 Pressure : Atmospheric

Reservour (G)1 Temperature: 32 degF

The diagnostic information is also included below:

=== Simulation (Elapsed: 9 sec) ===
    Error:An error occurred while running the simulation and the simulation was terminated
    Caused by:
        ['Gas_Expansion/Solver Configuration']: At time 0.000000, one or more assertions are triggered. See causes for specific information.
            Pressure at port A must be greater than or equal to Minimum valid pressure. The assertion comes from:
Block path: Gas_Expansion/Mass Flow Rate Source (G)
Assert location: 
    o In between line: 198, column: 9 and line: 198, column: 15 in file: C:\Program Files\MATLAB\R2020b\toolbox\physmod\simscape\library\m\+foundation\+gas\+sources\mass_flow_source.ssc
            Temperature at port A must be greater than or equal to Minimum valid temperature. The assertion comes from:
Block path: Gas_Expansion/Mass Flow Rate Source (G)
Assert location: 
    o In between line: 200, column: 9 and line: 200, column: 15 in file: C:\Program Files\MATLAB\R2020b\toolbox\physmod\simscape\library\m\+foundation\+gas\+sources\mass_flow_source.ssc
            Pressure at port B must be greater than or equal to Minimum valid pressure. The assertion comes from:
Block path: Gas_Expansion/Variable Orifice ISO 6358 (G)
Assert location: 
    o (location information is protected)
            Temperature at port B must be greater than or equal to Minimum valid temperature. The assertion comes from:
Block path: Gas_Expansion/Variable Orifice ISO 6358 (G)
Assert location: 
    o (location information is protected)
            Argument of log must be positive. The assertion comes from:
Block path: Gas_Expansion/Variable Orifice ISO 6358 (G)
Assert location: 
    o (location information is protected)

Answer 1

[Juan Sagarduy]

Hello Tiffy

The gas starts up in a suction state, which means that vacuum would be created in the system. Such situations occur easily in the gas domain.

Two things i would try would be: 1) smaller orifices 2) use of a pressure source instead of mass flow rate source.

Best of Luck / Juan

Answer 2

[SARA]

Hello @TiffyEng

Could you please find the solution of this error?

Thank you

Sara