Abstract An on-the-fly kinetic mechanism reduction scheme, referred to as dynamic adaptive chemistry (DAC), has been developed to incorporate detailed chemical kinetics into reactive flow computations with high efficiency and accuracy. The procedure entails reducing a detailed mechanism to locally and instantaneously accurate sub-mechanisms at each hydrodynamic time step of the calculation, and consequently no a priori information regarding simulation conditions is needed. The reduction utilizes an extended version of the directed relation graph (DRG) method in which the edges are weighted by a value that measures the dependence of the tail species (vertex) on the head species. An R -value is then defined at each vertex as the maximum of the products of these weights along all paths to that vertex from an initiating species. Active species are identified by their R -values exceeding a threshold value, e R , using a modified breadth-first search (BFS) that starts from a pre-defined set of initiating species. Chemical kinetics equations are then formulated with respect to the active species, with the inactive species considered only as third body collision partners. The DAC method is implemented into CHEMKIN and tested by simulating homogeneous charge compression ignition (HCCI) combustion using detailed and pre-reduced n -heptane mechanisms (578 species and 178 species, respectively) as the full mechanisms. The DAC scheme reproduces with high accuracy the pressure curves and species mass fractions obtained using the full mechanisms. The on-the-fly mechanism reduction scheme introduces minimal computational overhead and achieves more than 30-fold time reduction in calculations using the 578-species mechanism.
[1]
Heinz Pitsch,et al.
Systematic Reduction of Large Chemical Mechanisms
,
2005
.
[2]
P. I. Barton,et al.
Rigorous valid ranges for optimally reduced kinetic models
,
2006
.
[3]
Marianthi G. Ierapetritou,et al.
An adaptive reduction scheme to model reactive flow
,
2006,
Combustion and Flame.
[4]
C. Westbrook,et al.
A Comprehensive Modeling Study of n-Heptane Oxidation
,
1998
.
[5]
C. Law,et al.
A directed relation graph method for mechanism reduction
,
2005
.
[6]
William H. Green,et al.
An adaptive chemistry approach to modeling complex kinetics in reacting flows
,
2003
.
[7]
Chung King Law,et al.
Combustion at a crossroads: Status and prospects
,
2007
.
[8]
Robert J. Kee,et al.
CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics
,
1996
.
[9]
H. Curran,et al.
Extinction and Autoignition of n-Heptane in Counterflow Configuration
,
2000
.
[10]
Ellis Horowitz,et al.
Fundamentals of Data Structures
,
1984
.
[11]
Tianfeng Lu,et al.
Linear time reduction of large kinetic mechanisms with directed relation graph: N-Heptane and iso-octane
,
2006
.