Revisiting numerical issues of stochastic Eulerian-Lagrangian models

Three numerical issues of the stochastic Eulerian-Lagrangian models for two-phase turbulent flow computations are revisited. It is found that importance of the inlet condition of the dispersed-phase fluctuating velocity, u'(pi), on the solution of the fluctuating flow quantity of the dispersed phase, <u'(pi)²>, is appreciable for the large droplets (or particles). However, the neglect of the inlet u'(pi) condition which was made in the most stochastic Lagrangian computations does not introduce marked deviation in the determination of the mean dispersed-phase flow properties through use of the usual ensemble-averaging form. It is found that a great number of 10⁴ computational droplets for each discrete size is needed to attain a statistically stationary solution of <u'(pi)²>. Furthermore, the choice of the ensemble-averaging form is not important with the use of 10⁴ computational droplets for each discrete size in the stochastic Lagrangian computation.