Spontaneous imbibition of liquids in glass-fiber wicks. Part I: Usefulness of a sharp-front approach

What is it about?

In this paper, on using the single-phase Darcy's law, after assuming a sharp flow-front marked by full saturation behind the front, we modeled the spontaneous imbibition of a liquid into glass-fiber wicks as transversely isotropic porous medium. An analytical expression for the height of the wicking flow-front as a function of time is tested through comprehensive experiments involving using eight different wicks and one oil as the wicking liquid. A good fit with experimental data is obtained without using any fitting parameter.The proposed model provides a nice upper bound for all the wicks, thereby establishing its potential as a good tool to predict liquid absorption in glass-fiber wicks. However, the sharp-front model is unable to explain region of partial saturation.

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Why is it important?

In most application of wicking, it is important to predict the height of the liquid front as a function of time. In this investigation, we developed a theoretical model which is able to determine the actual height of the front for most cases that wicking happens with a clear sharp front into a wick.