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In this paper, a multiphase Lattice Boltzmann approach is adopted to directly simulate flow conditions that lead to the inception of cavitation in an orifice. Different values of fluid surface tension are considered, which play a dramatic role in the evolution of vapour cavity, as well as different inlet velocities at the computational domain boundary. The results of the flow simulations in terms of density and velocity magnitude fields are examined, with special focus on the components of the stress tensor inside the cavitating region: a comparison with cavitation inception criteria known form literature is proposed, highlighting the good agreement between our direct numerical simulations and theoretical predictions.

Spray formation and break-up are crucial phenomena for mixture formation inside diesel engines, both for combustion control and pollutant formation. Since the emission restrictions have become more and more severe in the last years, many studies have been conducted in order to improve diesel injection. Numerical simulations have proven to be reliable in producing results in a faster and cheaper way than experimental measures. The recent great progresses in computer science, then, have allowed to reach great accuracy in the simulations. In this work, a novel methodology based on Boltzmanns Kinetic Theory is applied to diesel injection. Lattice Boltzmann BGK (LBGK) provides and alternative method for solving fluid-dynamic problems and allows even superior accuracy as compared to conventional CFD. The multiphase approach used in this paper to study spray formation and primary is based on the works by Shan and Chen and their successive modifications.