Characterisation of pendular capillary bridges derived from experimental data using inverse problem method

Boleslaw Mielniczuk (1, 2, 3, 4) , Olivier Millet (1) , Gérard Gagneux (1) , Moulay Saïd El Youssoufi (2, 3, 4)

1 LaSIE - Laboratoire des Sciences de l'Ingénieur pour l'Environnement - UMR 7356
2 LMGC - Laboratoire de Mécanique et Génie Civil
3 SIGECO - Structures Innovantes, Géomatériaux, ECOconstruction
4 MIST - Laboratoire de micromécanique et intégrité des structures

In this study we use the recent analytical model to analyze capillary interactions in liquid bridge between two spherical grains, with fixed volumes of liquid and varying separation distance. Sequences of images of capillary bridges with different parameters are recorded during experimental tests. Geometrical parameters, as contact angle, half-filling angle and neck radius, are determined by image processing. Profiles of examined bridges are approximated as a Delaunay’s roulette and superposed on recorded images. Evolution of associated variables (Laplace pressure, capillary force) is also calculated. Results of theoretical modeling are compared with the experimental ones. They match very accurately for small volumes and/or small separation distances, when influence of gravity is not significant. For larger liquid volumes and/or larger separation distances between grains the influence of the gravity is observed as a distortion (loss of symmetry) of capillary bridge. To avoid this deformation, several test were realized in micro-gravity conditions. For these tests, theoretical results are in good agreement with experimental ones, also for higher liquid volumes and/or separations distances.

Mots clés: Inverse problem; Experimental measurement; Capillary bridge; Young–Laplace equation

Domaines: Mécanique des matériaux [physics.class-ph]

Boleslaw Mielniczuk, Olivier Millet, Gérard Gagneux, Moulay Saïd El Youssoufi. Characterisation of pendular capillary bridges derived from experimental data using inverse problem method. Granular Matter, 2018, 20 (1), pp.14. ⟨10.1007/s10035-017-0784-8⟩. ⟨hal-01710311⟩