Droplet homogeneous nucleation in a turbulent vapour jet in the two-way coupling regime

Homogeneous nucleation of liquid droplets in hot vapour stream, mixing with a cooler and dry external environment, occurs in many technological applications, ranging from the generation of filter test particles to the control of fugitive emissions from industrial sources (refineries), up to the young discipline of Particle Engineering in the biotech industries. However, a Direct Numerical Simulation (DNS) of a vapour jet is still missing, despite the multitude of experiments and its relevance for applications, which could benefit from a better understanding of such multi-physics turbulent flows. Classical Nucleation Theory (CNT) prescribes rates and critical diameters at which droplets nucleate, depending on the local thermodynamical state. Because of the strongly nonlinear interplay between homogeneous nucleation and turbulent fluctuations, it is crucial not only to take into account all the relevant scales of turbulence, but even all the cross-coupling phenomena involved. DNS allows to capture, without any modelling, the turbulence underlying the carrier phase dynamics. In the two-way coupling regime, the disperse phase back- reaction is then accounted within the point-particle approach. The relevance of these effects on the whole process of the phase-change, i.e. droplets nucleation, condensation and evaporation, will be discussed. In particular, it will be pointed out how much the droplets back-reaction, on the thermodynamics (especially due to the phase-change), does affect the subsequent droplets nucleation rate.