Numerical investigation of droplet evaporation and transport in a turbulent spray with LES/VSJFDF model

• The SGS effects of the velocity and scalars on the droplets are both considered.
• The joint PDF is used to derive the VSJFDF transport equation.
• The VSJFDF transport equation is derived for droplet evaporation and transport.
• The LES–VSJFDF model can clearly improve the accuracy of numerical results.

A velocity–scalar joint filtered density function (VSJFDF) transport equation was derived for the fluid flow field experienced by the particles in the evaporating gas–droplet two-phase flow. In this model, the large eddy simulation (LES) is used to simulate the fluid flow and the Lagrangian method is used to simulate the motion of the particle. In order to consider the sub-grid scale (SGS) effects of the gas velocity and scalar fluctuation transport and evaporation, we utilized the transport equation of the velocity–scalar joint filtered density function (VSJFDF) of the gas flow experienced by the droplets. With the developed LES/VSJFDF model, numerical simulations of an evaporating two-phase spray flow were carried out. The numerical results with the VSJFDF model, the VFDF (velocity filtered density function) model and non-FDF (filtered density function) model were compared with the experimental data, simultaneously. The comparison proved that the LES/VSJFDF model can definitely improve the accuracy of the prediction on the droplets׳ mean diameter.