Simscape gas pipe acoustics

I am modeling a gas circuit which experience resonance.

From the help I found that the pipe element assume the gas inertia to be negligible.

Is there another way to account for standing waves and resonance of the gas system?

[Caleb McFarlane]

Did you ever find a solution to this?

Answer 1

[Yifeng Tang]

You are probably right that you'll need the gas inertia modeled to capture the quick oscillation of pressure as the results of standing waves and resonance. There is an example of such phenomenon in the thermal liquid (TL) domain: https://www.mathworks.com/help/releases/R2022b/simscape/ug/water-hammer-effect.html

You'll need to make custom component, probably based on the existing Pipe (G) block, to include gas inertia in your gas network. The Pipe (TL) block has the options to enable or ignore inertia. So I think the best place for you to start is to compare the governing equations for with and without inertia in the TL domain, rewrite (if needed) for the gas domain, and try to add the additional equations in the .ssc files. Resources on Simscape language and customization: https://www.mathworks.com/help/releases/R2022b/simscape/get-started-with-simscape-language.html

In addition to the inertia, you may also need to enough spatial resolution, as in the example, to capture the traveling of the waves. Simscape blocks are "lump" models, so you need a few of them to resolve the wave shape.