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J P Hulin

Publications and source records attributed to J P Hulin.

5 recordsLinked to original sources
PubMed2005

Dewetting processes in a cylindrical geometry.

Dewetting of liquid films of water-glycerol solutions of different viscosities has been studied experimentally in PVC cylindrical tubes. In contrast with plane surfaces, the dewetting capillary number Ca(vd) increases with the film thickness ho over a large part of the experimental range and follows a same global trend independent of viscosity as a function of ho. This increase is only partly explained by variations of the capillary driving force predicted in a recent theoretical work for a cylindrical geometry. An additional explanation is suggested, based on different spatial distributions of the viscous dissipation in the dewetting bump in the planar and cylindrical geometries. This mechanism is investigated for films of different thicknesses in a numerical model assuming a polynomial variation of the liquid thickness with distance in the bump region.

Capillary Action↗
PubMed2004

Self-affine fronts in self-affine fractures: large and small-scale structure.

The evolution and spatial structure of displacement fronts in fractures with self-affine rough walls are studied by numerical simulations. The fractures are open and the two faces are identical but shifted along their mean plane, either parallel or perpendicular to the flow. An initially flat front advected by the flow is progressively distorted into a self-affine front with a Hurst exponent equal to that of the fracture walls. The lower cutoff of the self-affine regime depends only on the aperture, while the upper cutoff grows with the lateral shift and linearly with the width of the front.

Journal Article↗
PubMed2001

Experimental study of miscible displacement fronts in rough self-affine fractures.

Miscible fluid displacements are studied experimentally in a radial flow between two complementary replica of a self-affine rough granite fracture surface. The displacement front between a dyed fluid and a transparent (but otherwise identical) one is followed optically through one face of the cell. The evolution of its geometry is studied as a function of time, flow-rate, and normal and lateral relative displacements between the two surfaces. For a purely normal displacement, the front is globally smooth, due to the constant local distance between surfaces. For a finite lateral displacement, the front is rough due to spatial variations of this distance; its geometry is fractal and its dimension is directly related to the Hurst exponent H approximately 0.8 of the surface. The fractal regime is observed only above a lower cut-off scale that depends on the normal spacing of the surfaces and an upper one that increases with the injected volume and with the amplitude of the lateral displacement.

Journal Article↗
PubMed1996

Pulsed field gradient NMR measurements of probability distribution of displacement under flow in sphere packings.

In this work we used the PFG NMR displacement technique to investigate the transport of water particles under flow through a model porous media. Using different sizes of sphere for monodisperse glass sphere packings, we measured the probability distribution of displacement for mean displacements ranging from 0.08 to 7.3 times the characteristic length of the porous media. We observed, therefore, the transition between the velocity probability distribution and the Gaussian-shaped distribution of classical dispersion.

Glass↗