Simulation of turbulent bubbly pipe flow with high density ratio and high reynolds number by using the lattice boltzmann method and a multi-phase field model

Direct numerical simulation (DNS) has been widely employed to study the dynamics of turbulent bubbly flows; however, it is used in a limited setting, namely, turbulent bubbly channel flows with low density ratio and low Reynolds number. The present study aims to overcome these limitations and simulate turbulent bubbly pipe flow of a water-air system, a common experimental setting, with high density ratio and Reynolds number. Recently, we developed a cumulant lattice Boltzmann method for two-phase flows and simulated violent two-phase flows with high density ratio and high Reynolds number (Sitompul and Aoki, 2019). In this study, that method is extended by incorporating a multi-phase field model for simulating dispersed bubbles. The proposed method was evaluated by using several cases, namely, 3D bubble rising, turbulent single-phase channel and pipe flows with friction Reynolds number (Re_τ≈180,550), turbulent bubbly channel flows with (Re_τ≈180) and void fraction (α=1.5%,19.4%), and turbulent bubbly pipe flow with (Re_τ=550,α=9.5%). The proposed method can stably simulate the cases, and the results obtained by the proposed method agree well with numerical and experimental results given in the references for given computational domain and grid sizes.