Numerical Simulation of Unsteady Flow in Air-Lift Pump.

Abstract

A numerical method for simulation of unsteady flow in a large-scale air-lift pump, which is the main element of a deep-sea mining system, has been developed. We have proposed an iterative scheme for implicit time marching of density and pressure, and numerically simulated an air-water two-phase flow using a drift-flux model. In this paper, we describe improvements in the numerical scheme, especially for the convection term. First, convection terms are discretized based on the velocity component of each phase. Second, the finite difference method, which has excellent energy conservation properties, is applied. Then, the upstream-shifted interpolation technique is introduced. Numerical results for both unsteady and steady-state features show reasonable agreement with the experimental data obtained using an air-lift system of a depth of 200 m.