Time-resolved X-ray radiography of through-thickness liquid transport in partly saturated needle-punched nonwovens
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arXiv
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866915801222610944 |
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| author | Wegele, Patrick Yao, Zisheng Tejbo, Jonas Rogalinski, Julia K. Rosén, Tomas Groetsch, Alexander Nygård, Kim Asimakopoulou, Eleni Myrto Villanueva-Perez, Pablo Söderberg, L. Daniel |
| author_facet | Wegele, Patrick Yao, Zisheng Tejbo, Jonas Rogalinski, Julia K. Rosén, Tomas Groetsch, Alexander Nygård, Kim Asimakopoulou, Eleni Myrto Villanueva-Perez, Pablo Söderberg, L. Daniel |
| contents | Nonwoven fibre networks underpin filtration, insulation and geotextiles, where liquid uptake, redistribution and release govern performance. In needle-punched felts, barbed needles mechanically entangle fibres and partially reorient them toward the thickness direction ($z$), creating out-of-plane "pillars" and heterogeneity. While mechanical and structural consequences of needling are well documented, dynamic $z$-direction transport in partly saturated networks remains difficult to access due to opacity and sub-second timescales. Here we combine micro-CT ($μ$CT) of dry structure with time-resolved X-ray radiography during droplet addition to quantify through-thickness transport as a function of saturation and needling intensity, using a compact Washburn-type descriptor for dynamics. Results show an exponential dependence of $z$-directional liquid transport on saturation, consistent with previous models for in-plane relative permeability of nonwoven networks. Additionally, increased needle-punch intensity reorients fibres toward the $z$-direction, forming preferential flow pathways that enhance through-thickness transport, even as single-phase permeability decreases. These findings underscore needle-punch as a key design parameter for tuning liquid transport in nonwoven fibre networks. The approach provides an experimental and modelling framework for dynamic, capillarity-driven transport in opaque fibrous materials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_15176 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Time-resolved X-ray radiography of through-thickness liquid transport in partly saturated needle-punched nonwovens Wegele, Patrick Yao, Zisheng Tejbo, Jonas Rogalinski, Julia K. Rosén, Tomas Groetsch, Alexander Nygård, Kim Asimakopoulou, Eleni Myrto Villanueva-Perez, Pablo Söderberg, L. Daniel Fluid Dynamics Nonwoven fibre networks underpin filtration, insulation and geotextiles, where liquid uptake, redistribution and release govern performance. In needle-punched felts, barbed needles mechanically entangle fibres and partially reorient them toward the thickness direction ($z$), creating out-of-plane "pillars" and heterogeneity. While mechanical and structural consequences of needling are well documented, dynamic $z$-direction transport in partly saturated networks remains difficult to access due to opacity and sub-second timescales. Here we combine micro-CT ($μ$CT) of dry structure with time-resolved X-ray radiography during droplet addition to quantify through-thickness transport as a function of saturation and needling intensity, using a compact Washburn-type descriptor for dynamics. Results show an exponential dependence of $z$-directional liquid transport on saturation, consistent with previous models for in-plane relative permeability of nonwoven networks. Additionally, increased needle-punch intensity reorients fibres toward the $z$-direction, forming preferential flow pathways that enhance through-thickness transport, even as single-phase permeability decreases. These findings underscore needle-punch as a key design parameter for tuning liquid transport in nonwoven fibre networks. The approach provides an experimental and modelling framework for dynamic, capillarity-driven transport in opaque fibrous materials. |
| title | Time-resolved X-ray radiography of through-thickness liquid transport in partly saturated needle-punched nonwovens |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2602.15176 |