Modeling extinction and reignition in turbulent nonpremixed combustion using a doubly-conditional moment closure approach

The scalar dissipation rate is introduced as a second conditioning variable into the first-moment, singly conditional moment closure model to describe extinction and reignition effects in turbulent, nonpremixed combustion. A priori testing of the combustion model using direct numerical simulation experiments exhibiting local extinction/reignition events is described. The singly conditional moment closure model is either unable to describe the extinction seen in the numerical experiments or predicts global extinction when it does not occur. The new doubly conditional moment closure approach is able to describe the extinction seen on average, but predicts the onset of reignition too early. (C) 2001 American Institute of Physics.