arXiv subjects

L. Duchemin

Publications and source records attributed to L. Duchemin.

4 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↗

arXiv2024

Pinching Dynamics of Thin Films of Binary Mixtures

In binary mixtures, the lifetimes of surface bubbles can be five orders of magnitude longer than those in pure liquids because of slightly different compositions of the bulk and the surfaces, leading to a thickness-dependent surface tension of thin films. Taking profit of the resulting simple surface rheology, we derive the equations describing the thickness, flow velocity and surface tension of a single liquid film. Numerical resolution shows that, after a first step of tension equilibration, a parabolic flow with mobile interfaces is associated with film pinching in a further drainage step. Our model paves the way for a better understanding of the rupture dynamics of liquid films.

cond-mat.soft↗

arXiv2018

Tree crowns grow into self-similar shapes controlled by gravity and light sensing

Plants have developed different tropisms: in particular, they re-orient the growth of their branches towards light (phototropism) or upwards (gravitropism). How these tropisms affect the shape of a tree crown remains unanswered. We address this question by developing a propagating front model of tree growth. This model being length-free, it leads to self-similar solutions, independent of the initial conditions, at long time. Varying the intensities of each tropism, different self-similar shapes emerge, including singular ones. Interestingly, these shapes bear similarities with existing tree species. It is concluded that the core of specific crown shapes in trees relies on the balance between tropisms.

physics.bio-ph↗

arXiv2002

Inviscid coalescence of drops

We study the coalescence of two drops of an ideal fluid driven by surface tension. The velocity of approach is taken to be zero and the dynamical effect of the outer fluid (usually air) is neglected. Our approximation is expected to be valid on scales larger than $\ell_ν = ρν^2/σ$, which is $10 nm$ for water. Using a high-precision boundary integral method, we show that the walls of the thin retracting sheet of air between the drops reconnect in finite time to form a toroidal enclosure. After the initial reconnection, retraction starts again, leading to a rapid sequence of enclosures. Averaging over the discrete events, we find the minimum radius of the liquid bridge connecting the two drops to scale like $r_b \propto t^{1/2}$.

physics.flu-dyn↗