Dynamics of particle-scale liquid distribution in Pseudo-2D packed beds: Measurements and volume-of-fluid simulations

In this work, three-dimensional (3D) particle-resolved Volume-of-Fluid simulations of liquid spreading in pseudo-two-dimensional (pseudo-2D) beds as a function of liquid flow rate (Q(L)), gas/liquid flow rate ratio (Q(G)/Q(L)), and void-size (d(v)) are performed. The predictions are validated with the corresponding measurements performed using high-speed imaging in terms of liquid-holdup, interface length, and time-evolution of the gas-liquid interface. The relationship between the dynamics of liquid spreading and the governing forces is investigated using ABI, Weber (W-eI), and modified-Froude (Fr-m). Our analysis reveals that the liquid spreading through the pseudo-2D domain is predominantly governed by the gravitational force [AB(I) < 1]. As Q(L) increases, the relative magnitude of the inertial force becomes comparable to the gravitational force at the beginning of liquid injection [AB(I) similar to 1; We(I) > 1], enhancing lateral liquid spreading. An increase in Q(G)/Q(L) led to an increase in the gas-phase inertial force, which resists lateral liquid spreading. Moreover, the decrease in dv results in an increase in the relative contribution of inertial and capillary force at the beginning and final stages, respectively, leading to an increase in the lateral liquid spreading. A regime map relating the extent of lateral liquid spreading and governing forces is also proposed with the aid of AB(I), We(I), and Fr-m. Finally, the laterally oriented liquid bridges in the prewetted beds are found to facilitate liquid spreading in the lateral direction, leading to enhanced lateral liquid spreading in prewetted beds compared to dry beds.