Numerical Simulation of Gas-Liquid Flow in a Bubble Column by Intermittent Aeration in Newtonian Liquid/Non-Newtonian Liquid

Abstract

The dynamic behaviors of gas-liquid two-phase flow were simulated in a lab-scale intermittent bubble column by Euler-Euler two-fluid model coupled with the PBM (population balance model) using two different liquid phases, i.e., Newtonian fluid (water)/non-Newtonian fluid (activated sludge). When non-Newtonian fluid was used during intermittent aeration, some interesting results were obtained. Two symmetric vortexes existed in the time-averaged flow field; the vertical time-averaged velocity of the liquid phase decreased with increasing anaerobic time; the average gas holdup distribution was like a trapezoid with long upper side and short lower side and affected by the dynamic viscosity of the liquid phase. Compared with non-Newtonian fluid, the use of Newtonian fluid as the liquid phase led to a more complicated time-averaged flow field structure and vertical time-averaged velocity distribution, higher average gas holdup, and the asymmetric column-shaped gas holdup distribution with increasing anaerobic time. For different liquid phases, the instantaneous flow field, instantaneous vertical velocity, and instantaneous gas holdup distribution all periodically changed with anaerobic time; however, different from Newtonian liquid phase, non-Newtonian liquid phase had no periodic oscillating instantaneous horizontal velocity.

Homogeneous and re-circulatory gas–liquid flow in a bubble column: A numerical investigation using OpenFOAM

“…This is probably because of the existence of a wide range of bubble size distribution inside the column. In particular, the smaller bubbles oscillate in an irregular and chaotic manner [22]. In case of the local sparger (A7), where the disabled aerated portion is much higher compared to the rest of the sparger, the oscillating behavior is much stronger.…”

Bubble size distribution and gas holdup in bubble columns employing non‐Newtonian liquids: A CFD study

“…Anastasiou et al [ 4 ] determined the effective liquid viscosity as a function of the gas flow rate from the mean shear rate. The dynamics related to the bubble rise in CMC and xanthan gum solutions were investigated by Islam et al [ 60 ] The hydrodynamics of opaque non‐Newtonian liquids in bubble columns was examined by Wang et al [ 61 ] Xipeng et al [ 62 ] investigated the instantaneous and time‐averaged flow fields and velocity distributions in Newtonian and non‐Newtonian systems.…”