Role of the intake generated thermal stratification on the temperature distribution at top dead center of the compression stroke

This work investigates the role of the intake generated thermal stratification in the temperature field evolution during the compression stroke using direct numerical simulation. The analysis compares two direct numerical simulations during the compression stroke, from which one is initialized with a homogeneous temperature distribution and the other one with a stratified temperature field resulting from a precursor direct numerical simulation of the intake stroke. All other initial and boundary conditions are identically imposed. The results show that the thermal situation at bottom dead center has nearly no impact on the evolution of the temperature field and the wall heat transfer during compression. Dominating mechanism for the temperature field evolution is found to be the convective transport of cold gases from the boundary layers toward the cylinder center. As a consequence, the wall temperature and the flow field are the main influencing parameters controlling the evolution of the temperature dist...