Review of turbulent fluctuation effect on nano-particle two-phase flow system

The general dynamic equation (GDE) of micro/nano-particle in two-phase turbulence flow is presented, and the unclosed source terms induced by turbulent fluctuation are analyzed. The effects of turbulence fluctuation on the particle nucleation, condensation growth, coagulation and breakage are reviewed, including the modification of the source kernel function and Reynolds-average or subgrid -scale filtering to the GDE. The research results of solving the GDE using the method of direct numerical simulation (DNS), Monte Carlo, large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) simulation are described. The closed approach for solving the GDE is introduced: the correlation function is used to establish the relationship between the unclosed source term and the properties of particles and turbulent flow field, the probability density function (PDF) is directly substituted into the unclosed source term, and then the averaged values of the unclosed source term are obtained by statistical method. Some important problems of further study are discussed, including the effect of turbulence fluctuation on particle coagulation, experimental instruments and techniques, and targeted experimental research on the modeling of unclosed terms in the general particle dynamic equation.