CFD method for the liquid-gas two-phase flow fields in an Orbal oxidation ditch

This paper is concerned with a numerical simulation method for the flow fields in an Orbal oxidation ditch (OD). The velocity and pressure fields are obtained by solving the three-dimensional time-averaged Navier-Stokes equations and renormalized group k-epsilon turbulence model using Fluent 6.3.26. Combined with the multi-reference frame, the flow driven by a surface aerator was calculated. The finite volume method was used to discretize the differential equations; velocity and pressure were computed with the pressure-implicit with splitting of operators algorithm; and the simulation of free surface was carried out using the volume of fluid method. The numerical simulation was carried out according to the working conditions of the Orbal OD, and the simulated longitudinal velocities at the measuring points along the representative measuring lines were obtained. The comparison between the simulated longitudinal velocities and the experimental ones shows a better agreement, which essentially validates the reliability of the mathematical model. At last, the possible sources of various errors in the calculation and experiment are analyzed so as to beneficially improve the calculation and the measurement accuracy in the future.