Modelling strategies for liquid spreading in medical absorbents

The use of validated computational models to predict liquid spreading in fibrous materials is an important tool for understanding and optimising the function of absorbent products. The aim of this paper is to review these modelling strategies and their limitations. Experimental methods to find the closure relationships required as an input into Richards' equation (which describes the fluid transport in porous materials) are discussed. The computational models are validated against the detailed laboratory experiments of the flow of fluid from sources on inclined or horizontal homogeneous fibrous sheets, and are extended to inhomogeneous layered structures. Recent progress towards modelling simple incontinence products is described.