Depinning and dynamics of imbibition fronts in paper under increasing ambient humidity.

We study the effects of ambient air humidity on the dynamics of imbibition in a paper. We observed that a quick increase of ambient air humidity leads to depinning and non-Washburn motion of wetting fronts. Specifically, we found that after depinning the wetting front moves with decreasing velocity v[proportionality](h(p)/h(D))(γ), where h(D) is the front elevation with respect to its pinned position at lower humidity h(p), while γ=/~1/3. The spatiotemporal maps of depinned front activity are established. The front motion is controlled by the dynamics of local avalanches directed at 30° to the balk flow direction. Although the roughness of the pinned wetting front is self-affine and the avalanche size distribution displays a power-law asymptotic, the roughness of the moving front becomes multiaffine a few minutes after depinning.

Citation

Alexander S Balankin, H Zapata López, E Pineda León, D Morales Matamoros, L Morales Ruiz, Dan Silva López, M A Rodríguez. Depinning and dynamics of imbibition fronts in paper under increasing ambient humidity. Physical review. E, Statistical, nonlinear, and soft matter physics. 2013 Jan;87(1):014102

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PMID: 23410468

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