Modification of the K-ε turbulence model for in-cylinder gas flow

A modification of the values of three constants C₁, C₂ and C₃ in the standard K-ε turbulence model is proposed, based on the empirical law of decay obtained for nearly homogeneous in-cylinder turbulence. Since the decay exponent of Reynolds numbers for in-cylinder turbulence is found to be different from that for steady ducted flow just behind a turbulence-generating grid, the C₂ value is modified first, followed by the C₁ and C₃ values, which depend on the C₂ value. The derived C₂ value of 1.40 is smaller than that in the standard K-ε turbulence model, but the C₁ value, 1.40 is close to that of the standard one. The C₃ value, -1.05, is very close to the recommended value by Morel et al. for the case of a unidirectional axial compression.