[niriosrat]

Actually, I am working in the CFD modeling of multiphase flow in vertical pipes using the eulerian multiphase model. Using the Schiller-Naumann method to calculate the drag force coefficient the simulations don’t have any problem. However, this simulation configuration presents not accurate results. For this reason, I am studying the performance of the eulerian multiphase model, where the drag force coefficient is calculated with a drift flux model. For this reason, I am using the linearized drag force method that follows the following equation:

F_ij^D=A_ij^D (v_j-v_i )

Where the linearized drag force coefficient is calculated with the following equation:

A_ij^D=3/4 C_ij^D (α_j ρ_i)/d_j |u_j-u_i |

Additionally, the drag coefficient equation is:

C_ij^D=4/3 (ρ_i-ρ_j)/ρ_i gd_j 1/(u_D^2 )

Where the Ud will be the drift velocity equation of a Drift-Flux model. I have tried 19 different models but I get convergence problems. I am using a field function to write the linearized drag force coefficient. Anyone have model this problem who can tell me which drift-flux model can I use? Or how can I modify the solvers parameters to avoid this convergence problems?

Thanks,