Minimum resistance radius for gas-liquid spontaneous imbibition in microtubes

Spontaneous imbibition is the natural movement of a wetting phase liquid within porous media or microtubes. Such flow occurs commonly in nature and industrial settings, where gas and liquid phases flow spontaneously through porous materials. To delve deeper into the characteristics and mechanisms of gas-liquid two-phase spontaneous imbibition at the microscale, this paper establishes a mathematical model considering acceleration. Through both numerical simulations and experiments, the detailed analysis of de-ionized water's spontaneous imbibition within microtubes sheds light on interface phenomena at the microscale. The results highlight the pronounced influence of the microtube radius and gas-water interfacial tension on the imbibition process. By combining experimental work, theoretical analysis, and numerical simulations, this study identifies the minimum resistance radius-a tube radius leading to the shortest imbibition time to the top. The research underscores the significance of considering acceleration and provides a theoretical groundwork for leveraging spontaneous imbibition. It also holds potential value for applications in microfluidic technology, nanomaterial synthesis, and biomedical fields.