A Dynamic Subgrid-scale Model for Les of the G-equation

Turbulent combustion is a di cult subject as it must deal with all of the issues found in both turbulence and combustion We consider only premixed ames in this paper but some of the ideas can be applied to the non premixed case As in many other elds there are two limiting cases that are easier to deal with than the general case These are the situations in which the chemical time scale is either much shorter or much longer than the time scale associated with the turbulence We deal with the former case In this limit the ame is thin compared to the turbulence length scales and can be idealized as an in nitely thin sheet This is commonly called the amelet regime it has been the subject of many papers and the basis for many models see e g Li n an Williams In the amelet model the local ame structure is assumed to be identical to the laminar ame structure thus the ame propagates normal to itself at the laminar ame speed SL This allows the use of simple approximations For example one expects the rate of consumption of fuel to be proportional to the area of the ame surface This idea allowed Damk ohler to propose that the wrinkled ame could be replaced by a smooth one which travels at the turbulent ame speed ST de ned by ST SL AL Ap