Economical, geopolitical and social trends, apart from the well-posed environmental concerns, are possible to precipitate legislative actions for the partial substitution of Diesel by cleaner fuels in the imminent future. Besides, the already stringiest emission legislation referring to Diesel engines, e.g. EURO VI or Tier IV standards, in Europe and in the US, have boosted industrial interest on the development of IC engines capable of handling both liquid/gaseous fuel mixtures. The combustion process in these, so-called, dual-fuel engines comprises the compression ignition of Diesel fuel injected in a homogenized gaseous (or liquid) fuel/air mixture. The underlying cause is that at dual-fuel combustion, most Diesel fuel is burned in premixed combustion and, thus, soot formation is less. Furthermore, depending on the carbon content of the primary gaseous (or liquid) fuel, dual fuel operation mode can lead to significant decrease in CO2 emission. Hence, natural gas or methane constitute ideal candidates among hydrocarbons. The aim of this project, in line with European and international policies in this area, is to develop and validate DNS/LES methodologies for fuel injection, mixing and combustion processes relevant to conditions and fuels combustion strategies realised in dual-fuel engines. Furthermore, to apply the newly derived models to the design of more efficient engines and to estimate the environmental impact of the proposed concept. Related to MSCA agenda, the project will create a unique opportunity for joint industry-academia PhD training to the fellows in world leading multinational industries. This will equip them with skills, knowledge and knowhow that will not only enhance their future careers but propose solutions to global problems and thus, serve the well-being of the society as a whole.