Fraunhofer Institute for Industrial Mathematics ITWM
Fraunhofer Institute for Industrial Mathematics ITWM
Windeln
© iStockphoto
Accessory set for Baby disposable diapers on a turquoise background tree, items for baby care. Lay diaper nappy, the parent taking care of a baby. safe baby ear sticks

The cellulosic fibrous layer is one of many different layers used in modern hygiene products to control and steer the flow of a liquid. For example, in diapers.

© iStockphoto

Cellulosic Materials

Fluid Transport in Hygiene Products

It was the aim of this project to determine numerically the effective transport properties of a cellulosic layer. This fibrous layer is one of many different layers used in modern hygiene products to control and steer the flow of a liquid. To improve the functionality of this product, it is very helpful to know the permeabilities and capillary pressure-saturation curves of all the different materials and layers used. Computer simulations allow to determine these parameters and thus enable to engineer new materials virtually.

Structure Model with GeoDict

To capture the structure of the cellulosic material samples, three-dimensional computer tomography images were taken. These 3D images were segmented and thus three-dimensional geometric structure models of the layer were obtained. By using ITWM's software tool GeoDict directional and saturation-dependent permeability and capillary pressure curves were calculated on these models. Here, the main difficulty is the size of tomographic images. A single 3D image may consist of up to 4000³ voxels, i. e. may require 60 GB!

Cellulosefaser
© ITWM
Cellulosic fibres
Cellulosefaser
© ITWM
Cellulosic fibres

Virtual Cellulose Fiber Media

Modell der Cellulose Faserschicht
© ITWM
Modell of the cellulose fiber layer with an inhomogeneous distribution of fibers created by GeoDict

However, the determination of material parameters based on CT scans is only the first step, as it only allows to investigate already existing materials. To study the impact of possible material variations on the product, virtually constructed structure models are needed. GeoDict allows to create these models (see Fig 1). In this project we investigated, how the inhomogeneous fiber distribution (as seen in Fig. 1) influences the transport properties. For this, structure models with an uniform fiber distribution were compared to structure models with fiber agglomerates.

Project partners:

Procter&Gamble

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