Premixed one-dimensional free propagating flames are difficult to converge when setting up multiple components

[Xinyuan Bai]

I am setting up a set of ammonia premixed flames, and the initial component settings are in the form of specified mass fractions. I have set the mass fractions of more than twenty components. However, in practical calculations, it is difficult to obtain a convergent solution. When I change some very low values (such as values below 10e-5) to 0 and reduce the initial number of components to 5, I can calculate the convergence solution well again. So I have a preliminary suspicion, is it difficult for Cantera to handle such complex initial quality score conditions?

[Ray Speth]

Hi,

Can you please provide a complete example? What exactly is the failure mode?

If I had to guess, the problem may be that some of your initial components are sufficiently reactive at the inlet that you aren't satisfying the inlet boundary conditions for the freely propagating flame, which require the reaction rates at the inlet to be approximately equal to zero.

Regards,

Ray