Application of multiple mapping conditioning mixing model to non-reacting spray a

The further development of compression-ignition engines would be facilitated by the availability of sufficiently general combustion models capable of accounting for all relevant in-cylinder processes, which include multi-mode combustion, fast and slow kinetics, and significant interactions of turbulence and chemistry. The transported probability density function approach (TPDF) is one method that, in principle, can account for all these phenomena. The TPDF approach requires a model for molecular mixing to represent transport in composition space. Experience with nonpremixed and premixed flames has shown that the property of localness (i.e. mixing occurring between fluid regions having similar compositions) is beneficial for model performance. On the basis of this observation, a novel multiple mapping conditioning (MMC) based mixing model has been proposed recently in which mixing is conditioned on a reference scalar that is statistically similar, but not identical to mixture fraction. The model has been found to perform well in the context of single-phase nonpremixed combustion due to its localness property. In the present work, the MMC mixing model is validated against the non-reacting Engine Combustion Network (ECN) spray-A case to test its applicability to multi-phase flows. Mass consistency is a major issue in PDF algorithms and a robust coupling between the spray and gas field ensures that the mass conservation law is not violated. The simulation results are validated using liquid length, vapour penetration and mixture-fraction field data. The degree of control over the obtained localness is assessed by comparing statistics of mixture fraction and the reference scalar.