Recent studies have shown that a reasonable initial distribution can significantly reduce the transition time from initialization to reaching steady state for simulation of a riser.In this work

a series of simulations were performed to study the relationship between initial conditions and simulation efficiency.The results indicated that statistically-averaged distribution could be an effective initial distribution.Then

all the flow parameters for defining this initial distribution(i.e.pressure

gas and solids velocities

voidage) were investigated respectively for sensitivity analysis.It was found that transition time could be reduced greatly if a good axial distribution of voidage was provided at the beginning of the simulation.This finding was confirmed further by a hydrodynamical simulation of gas-solids flow in a riser with EMMS(energy-minimization multi-scale) model

in which EMMS model was used to provide a reasonable axial voidage distribution as the initial condition.The relevant results

such as solids flux

were in good agreement with experimental data.