Dynamics of liquid flow through fabric porous media: Experimental, analytical, and numerical investigation

Over the past few decades, there has been a significant increase in the use of paper-based microfluidic devices in various fields, including environmental monitoring, food safety analysis, and medical diagnostics. As a result, flow through paper-based substrates has gained much attention in the research community. Liquid flows through a paper substrate due to the inherent capillary suction pressure. In order to predict the flow through a paper substrate, we used macro- and microscopic methodologies to construct an analytical and numerical model. We have considered the effect of different factors, e.g., roughness, swelling, dynamic contact angle, and evaporation simultaneously to predict liquid wicking. A modified capillary radius technique is used to incorporate the effects of roughness and swelling into the numerical model, while a sink factor in Darcy's equation is used to model the evaporation. Experiments are performed to validate the developed models, and it is found that both models are in good agreement with the experiments, with a maximum error of 5%. The proposed analytical and numerical models can be used to forecast the capillary rise in a paper-based substrate, which has implications for paper-based microfluidic devices.