Unsteady premixed strained flame

[Shang-Ru Li]

Hi,

I have been using Ember, a Cantera-based solver, for some time. My goal is to simulate a counterflow premixed flame subject to a time-varying equivalence ratio. I am interested in carrying out a study similar to what is described in OPUS, but Ember is currently the only solver I have access to.

I was wondering whether there is a way in Ember to prescribe or fix the inlet velocity directly. I have customized the example_twin case quite a bit, including adding a time-varying equivalence ratio and fixing the right inlet location. However, as I understand it, Ember determines the velocity field through the strain-rate formulation rather than by imposing the inlet velocity directly.

To work around this, I tried implementing a PI controller at the right boundary to adjust the effective strain rate so that the right inlet velocity approaches a prescribed target. However, the results have not been satisfactory, and the velocity response does not appear to be robust.

Could you let me know whether fixing the inlet velocity is possible within Ember’s formulation, or whether this would require a more fundamental modification of the continuity/strain-rate treatment?

Best regards,

Shang-Ru