CFD-based non-equilibrium wall heat transfer models for engine-relevant conditions

The goal of this research is to contribute towards the development of predictive, physics-based computational fluid dynamics (CFD) models for studying advanced internal combustion (IC) engines with high efficiency and low emissions. The lack of accurate submodels for in-cylinder heat transfer has been identified as a key shortcoming to this end. Recent measurements of wall layers in engines show discrepancies of up to 100% with respect to standard CFD boundary-layer models. Additionally, available experimental data are quite sparse (only a few data points on engine walls) and limited (available measurements are those of heat flux only). Predictive submodels are needed for medium-resolution engineering LES and for unsteady Reynolds-averaged simulations (URANS). Recently, some research groups have performed DNS studies on engine-relevant conditions using simple geometries which provide very useful data for benchmarking computational models. While some recent sophisticated (one-equation) models have been incorporated as a part of the current work, others of a more detailed nature are underway. These include solving additional partial differential equations (PDEs) within the thin boundary layer near the wall and fall under the category of non-equilibrium models. The main aim of this project is to develop such two-zone models for engine wall heat transfer and to test them against available DNS/experimental data in both SI (spark-ignition) and CI (compression-ignition) engines. Ultimately it is also intended to include the effect of radiation in these models.