In the combustion simulation，can I fix the mass fraction of species on the bc?

[Here-Liu]

if we have a cylinder in the domain, can i fix the mass fraction of species on the cylinder like fix the temperature?

[drummerdoc]

We don’t allow that by default since that would lead to mass diffusion into the surface. If that’s what you want, we’d need a way to enforce that the sum of the species diffusion fluxes was zero. You could do that, but the proper way would likely be problem-dependent at best.

OTOH, if you cylinder surface wasn’t actually meant to be a material boundary, but rather a numerical interface into another domain or some such idea, you may want this. So maybe it’s best to ask what your plans were.