Effect of Externally Applied Liquid Pressure on Wicking in Paper Wipes

Wicking of liquid under externally applied liquid pressure into three paper wipes is studied for the first time. Darcy's law and capillary-tube flow form the basis of two separate theoretical models which were tested through experiments. The wicking and wetting parameters of the tested wipes were measured independently to enable such a comparison without the use of any fitting parameters. Darcy model is found to work better under zero hydraulic pressure, i.e. pure wicking; however capillary model is more accurate when the incoming liquid is pressurized. An increase in the applied pressure led to an increase in the liquid absorption rate and a decrease in the saturation time. However, its relative effect on the absorption rate and saturation time was found to decrease with an increase in its magnitude.