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Compressed Air filling in near vacuum chamber

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Old   May 3, 2017, 11:23
Default Compressed Air filling in near vacuum chamber
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There is a 20L sphere with an inlet pipe.

I have modeled input data for different time steps (discrete)
there is data for velocity, mass flux, mass flow, pressure, temperature, density for time step increments of different orders (i.e. 0.001, 0.0001, 0.00001, 0.000001 s)

These are discrete values, so I generate a graph of mass flux vs time step in excel and create a trend line and get a mass flux equation varying with each time step increment. I create a UDF function in C based on this massfluc(t). I input this at the inlet boundary (2D edge at the end of pipe).

either temperature is diverging, or non-physical solution.

I patch the sphere and tube initially with 300 K and 0.4 bar pressure.
I initialize with standard initialization and gauge pressure as 21bar.

I need to track the expansion process of the inlet air inside the sphere. What am I doing wrong, do you have a simulation strategy

This is a transient, compressible flow simulation
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air filling, compressible flow, gas filling, gas pump, transient

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