arXiv subjects

A. Eddi

Publications and source records attributed to A. Eddi.

7 recordsLinked to original sources

arXiv2026

Coalescence of viscous blisters under an elastic sheet

We study the coalescence of identical viscous blisters beneath an elastic sheet both experimentally and numerically. Using a time-resolved synthetic schlieren technique, we measure the evolution of the thickness field of the merging blisters and more specifically the dynamics of the coalescence region. To explain this dynamics, we develop a one-dimensional model based on the lubrication approximation, from which we derive scalings to predict the growth of the coalescence neck. We also numerically solve the full non-linear equation to assess the theory and compare to experiments. Our model illustrates that, at short times, the dynamics of coalescence is mainly controlled by the bending of the elastic sheet, leading to a relationship between the coalescence speed and the radius of curvature of the interface at the coalescence neck.

physics.flu-dyn↗

arXiv2025

Distributed network of smartphone sensors: a new tool for scientific field measurements

Smartphones sensors are now commonly used by a worldwide audience thanks to their availability, high connectivity, and versatility. Here, we present a methodology to use a collection of smartphones, namely a fleet, as a distributed network of time-synchronized mechanical sensors. We first present the mechanical tests we develop to evaluate the smartphone sensor accuracy. We then describe how to use efficiently a distributed network of smartphones as autonomous sensors. We use a combination of an Android application hosted on each phone (Gobannos), and a server application (Phonefleet) on a controlling host to perform the tasks in parallel remotely. We implement in particular a time synchronization protocol based on UDP communication. We achieved an accuracy of the smartphone clock synchronisation of 60 microseconds. Using two test cases in realistic outdoor conditions, we eventually prove the reliability of a smartphone fleet to measure mechanical wave measurements in field conditions.

physics.ins-det↗

arXiv2024

Measuring the local mechanical properties of a floating elastic sheet

Polar regions are covered by sea ice, which can be seen as a thin solid elastic sheet with heterogeneous mechanical properties. The dynamics of deformation of a floating solid sheet are primarly governed by gravity, water density, and the flexural modulus, which depends on its mechanical properties, namely the thickness, the Young's Modulus and the Poisson ratio. Non-invasive methods from seismology can retrieve these three parameters from sheet deformation dynamics. In this article, we developed another method to extract locally the flexural modulus of a floating thin elastic sheet from the spatio-temporal deformations of the sheet. We perform laboratory experiment to test the accuracy and the robustness of this method on silicon membranes of controlled mechanical properties. Using patches of different thicknesses and shapes, we eventually draw maps of sheet thickness, with a sub-wavelength spatial resolution.

physics.flu-dyn↗

arXiv2020

How capillarity affects the propagation of elastic waves in soft gels

Elastic waves propagating at the interface of soft solids can be altered by the presence of external forces such as capillarity or gravity. We measure the dispersion relation of waves at the free surface of agarose gels with great accuracy, revealing the existence of multiple modes as well as an apparent dispersion. We disentangle the role of capillarity and elasticity by considering the 3D nature of mechanical waves, achieving quantitative agreement between theoretical predictions and experiments. Notably, our results show that capillarity plays an important role for wavenumbers much smaller than expected from balancing elastic and capillary forces. We further confirm the efficiency of our approach by including the effect of gravity in our predictions and quantitatively comparing it to experiments.

cond-mat.soft↗

arXiv2019

Dispersion free control of hydroelastic waves down to sub-wavelength scale

Hydroelastic surface waves propagate at the surface of water covered by a thin elastic sheet and can be directly measured with accurate space and time resolution. We present an experimental approach using hydroelastic waves that allows us to control waves down to the sub-wavelength scale. We tune the wave dispersion relation by varying locally the properties of the elastic cover and we introduce a local index contrast. This index contrast is independent of the frequency leading to a dispersion-free Snell-Descartes law for hydroelastic waves. We then show experimental evidence of broadband focusing, reflection and refraction of the waves. We also investigate the limits of diffraction through the example of a macroscopic analog to optical nanojets, revealing that any sub-wavelength configuration gives access to new features for surface waves.

physics.flu-dyn↗

arXiv2013

How geometry determines the coalescence of low-viscosity drops

The coalescence of water drops on a substrate is studied experimentally. We focus on the rapid growth of the bridge connecting the two drops, which very quickly after contact ensues from a balance of surface tension and liquid inertia. For drops with contact angles below $90^\circ$, we find that the bridge grows with a self-similar dynamics that is characterized by a height $h\sim t^{2/3}$. By contrast, the geometry of coalescence changes dramatically for contact angles at $90^\circ$, for which we observe $h\sim t^{1/2}$, just as for freely suspended spherical drops in the inertial regime. We present a geometric model that quantitatively captures the transition from 2/3 to 1/2 exponent, and unifies the inertial coalescence of sessile drops and freely suspended drops.

physics.flu-dyn↗

arXiv2012

Symmetric and Asymmetric Coalescence of Drops on a Substrate

The coalescence of viscous drops on a substrate is studied experimentally and theoretically. We consider cases where the drops can have different contact angles, leading to a very asymmetric coalescence process. Side view experiments reveal that the "bridge" connecting the drops evolves with self-similar dynamics, providing a new perspective on the coalescence of sessile drops. We show that the universal shape of the bridge is accurately described by similarity solutions of the one-dimensional lubrication equation. Our theory predicts a bridge that grows linearly in time and stresses the strong dependence on the contact angles. Without any adjustable parameters, we find quantitative agreement with all experimental observations.

physics.flu-dyn↗