[sahmed]

Dear all
I want to share an issue with you and asking for your suggestion. This might be helpful for the reactive flow simulation community as well.
I am trying to simulate a reactive flow through a flow tube and the flue gases are coming from a Mckenna burner, burning lean syngas/air. First I did not simulate the flame, rather the post flame hot gases, coming from the burner. No combustion happened in that case. There I got a very good jet and a recirculation bubbles (please see the attached post flame simulation figures) when it reached Steady state condition in 3 secs..

But when I simulated the flame+post flame with combustion happening, within a very short time (~1 sec), the bubble got stretched and the jet did not break (see the attached flame simulation figures). Since the mesh needs to be very very fine for capturing the flame, I took a shorter domain length, but should still be ok to assume a zero-gradient BC at the outlet.

Could anyone please tell me why is this 'bubble stretching' happening when I have combustion and not happening without any combustion.

[sahmed]

Anybody has any idea or suggestion or comment, or anyone faced similar kind of problem for other cases, PLEASE share.

[sahmed]

Dear Foamers
Please share your thoughts about the issue.