COMPUTATIONALLY EFFICIENT IMPLEMENTATION OF COMBUSTION CHEMISTRY USING IN-SITU ADAPTIVE TABULATION

A computational technique is described and demonstrated that can decre ase by three orders of magnitude the computer time required to treat d etailed chemistry in reactive flow calculations. The method is based o n the in situ adaptive tabulation (ISAT) of the accessed region of the composition space-the adaptation being to control the tabulation erro rs. Test calculations are performed for non-premixed methane-air combu stion in a statistically-homogeneous turbulent reactor, using a kineti c mechanism with 16 species and 41 reactions. The results show excelle nt control of the tabulation errors with respect to a specified error tolerance; and a speed-up factor of about 1000 is obtained compared to the direct approach of numerically integrating the reaction equations . In the context of PDF methods, the ISAT technique makes feasible the use of detailed kinetic mechanisms in calculations of turbulent combu stion. The technique can also be used with reduced mechanisms, and in other approaches for calculating reactive flows (e.g. finite differenc e methods).