A Mixing Timescale Model for PDF Simulations of LTC Combustion Process in Internal Combustion Engines
Transported probality density function (PDF) methods are currently being pursued as a viable approach to model the effects of turbulent mixing and mixture stratification, especially for new alternative combustion modes as for example Homogeneous Charge Compression ignition (HCCI) which is one of the advanced LTC concepts. Recently, they have been applied to simple engine configurations to demonstrate the importance of accurate accouting for turbulence/chemistry interactions. PDF methods can explicity account for the turbulent fluctuations in species composition and temperature relative to mean value. The choice of the mixing model is an important aspect of PDF approach. Different mixing models can be found in the literature, the most popular is the IEM model (Interaction by Exchange with the Mean). This model is very similar to the LMSE model (Linear Mean Square Estimation).