Reply To: Mass Conservation Issue in Methane Pyrolysis Shock Tube Simulation

[ghislain_madiot]

Hi,

I conducted a test using CO2 as the driver gas, with CH4 and CO2 as the final species. I had to stop the extraction simulation when the mass error reached 0.4% and continued to increase after just 100 iterations, though at a slower rate compared to when CH4 was the last species.

 

I also compared another chemistry solver, Stiff Chemistry, with the Non-Explicit method using H2 as the driver gas, as this sceanrio has previously shown the most significant error.

I've attached contour plots for density, temperature, and pressure, as well as the residuals for these simulations.

The new solver notably reduced the mass balance error to just 0.05%, indicating that mass conservation is now satisfactory. However, in terms of mass conservation through the reactions, the non-explicit method still shows considerable deviation. While Stiff Chemistry performs better, there's still an 8% discrepancy between the mass of CH4 produced and the (carbon – H2 created)