arXiv subjects

David Bouttes

Publications and source records attributed to David Bouttes.

4 recordsLinked to original sources

arXiv2025

Gelation effects on the spreading of non-Newtonian drops impacting a reactive liquid

We report in this experimental and numerical study effects of gelation on the early-time spreading ($<$ 10ms) of millimetric non-Newtonian drops of biopolymer and particle suspensions impacting a Newtonian liquid containing reactive compounds. Our analyses are initially conducted through experiments by considering a variety of biopolymer and gelling compound concentrations, and impact velocities. The experimental results are then compared to three-dimensional numerical simulations based on a variational multiscale approach, which focuses on the impact of simple viscoplastic drops on a liquid bath in the absence of gelation (non-reactive liquid). These comparisons enable the development of theoretical arguments that emphasise relevant gelation effects on the drop's maximum spreading.

physics.flu-dyn↗

arXiv2016

Topological symmetry breaking in viscous coarsening

The crucial role of hydrodynamic pinch-off instabilities is evidenced in the coarsening stage of viscous liquids. The phase separation of a barium borosilicate glass melt is studied by in-situ synchrotron X-Ray tomography at high temperature. The high viscosity contrast between the less viscous phase and the more viscous phase induces a topological symmetry breaking: capillary breakups occur preferentially in the less viscous phase. As a result, contrasting morphologies are obtained in the two phases. This symmetry breaking is illustrated on three different glass compositions , corresponding to different volume fractions of the two phases. In particular, a fragmentation phenomenon, reminiscent of the end-pinching mechanism proposed by Stone et al. [1, 2] is evidenced in the less viscous phase.

cond-mat.soft↗

arXiv2015

Hydrodynamic coarsening in phase-separated silicate melts

Using in-situ synchrotron tomography, we investigate the coarsening dynamics of barium borosilicate melts during phase separation. The 3-D geometry of the two interconnected phases is determined thanks to image processing. We observe a linear growth of the size of domains with time, at odds with the sublinear diffusive growth usually observed in phase-separating glasses or alloys. Such linear coarsening is attributed to viscous flow inside the bicontinuous phases, and quantitative measurements show that the growth rate is well explained by the ratio of surface tension over viscosity. The geometry of the domains is shown to be statistically similar at different times, provided that the microstructure is rescaled by the average domain size. Complementary experiments on melts with a droplet morphology demonstrate that viscous flow prevails over diffusion in the large range of domain sizes measured in our experiments (1 - 80 microns).

cond-mat.mtrl-sci↗

arXiv2014

Fragmentation and Limits to Dynamical Scaling in Viscous Coarsening: An Interrupted in situ X-Ray Tomographic Study

X-Ray microtomography was used to follow the coarsening of the structure of a ternary silicate glass experiencing phase separation in the liquid state. The volumes, surfaces, mean and Gaussian curvatures of the domains of minority phase were measured after reconstruction of the 3D images and segmentation. A linear growth law of the characteristic length scale $\ell \sim t$ was observed. A detailed morphological study was performed. While dynamical scaling holds for most of the geometrical observables under study, a progressive departure from scaling invariance of the distributions of local curvatures was evidenced. The latter results from a gradual fragmentation of the structure in the less viscous phase that also leads to a power-law size distribution of isolated domains.

cond-mat.soft↗