Numerical investigations of two-phase finger-like instabilities.

• Computed results are provided with the help of three two-phase flow models: Baer and Nunziato, Marble , Saurel et al. • It is shown that the only model able to reproduce qualitatively finger-like jets is the dense dilute model of Saurel et al. • Viscous drag alone is unable to reproduce finger-like jets and non conservative terms seem responsible for jetting effects. The aim of the present work is to progress in the identification of the effects responsible for the formation of jets in heterogeneous gas-particle cylindrical and spherical explosions. In this direction three two-phase flow models are considered, namely Baer and Nunziato's (BN) (1986) model, Marble's (1963) model and the dense-dilute model of Saurel et al. (2017). The first and third ones involve both non-conservative terms and viscous drag effects while the second one involves viscous drag only as interaction force. Computed results show that viscous drag alone is unable to reproduce finger-like instabilities. The BN model and the dense-dilute one differ significantly by their acoustic properties. It is shown that the only model able to reproduce qualitatively finger-like jets is the dense-dilute model. Mesh dependence of the results is studied as well as presence or absence of viscous drag. It appears that the non-conservative terms seem responsible for jetting effects. [ABSTRACT FROM AUTHOR]