Colloquium
3:30 p.m., Friday
Math 100
Professor Anne Bourlioux
University of Montreal
Small scale asymptotic models for large scale simulations of
turbulent premixed flames
Replacing a finite thickness premixed flame by its asymptotic limit of
a zero thickness interface (flamelet) separating burnt and unburnt gas
is a rigorous procedure for laminar flows. However, most flows of
interest are turbulent, in which case the assumptions for the flamelet
asymptotic model are not quite satisfied. Still, it is computationally
convenient to retain the laminar flamelet representation to compute the
large scales of a turbulent premixed flame and to model the effects of
the small scales (unresolved in any practical computation). In this
talk, I will review the basic asymptotic laminar flamelet formulation
and also recent theoretical results for the turbulent case. Some of the
results have somewhat surprising and counterintuitive consequences
with regards to practical large scale flamelet codes. In particular,
it turns out that turbulence models based on the laminar flamelet
assumption can be systematically biased towards overpredicting the
turbulence effects. As an alternative, I will present a new numerical
strategy based on a rigorous asymptotic model to parameterize the
effective subgrid burning speed for a variety of smallscale
turbulentlike flow fields.
Refreshments will be served in Math Annex Room 1115, 3:15 p.m.
