simeon djambov

Welcome to my web page! I am a postdoctoral associate at LadHyX, working with Etienne Jambon-Puillet. Prior to this, I completed my Ph.D. in Mechanics under the supervision of Prof. François Gallaire in the Laboratory of Fluid Mechanics and Instabilities at EPFL. The scope of my thesis lies at the intersection of thin-film hydrodynamics and geomorphogenesis.

I am originally from Sofia and presently based in Paris-Saclay. I hold a Bachelor's degree in Physics from Université de Bordeaux and a Master's degree in Fundamental Physics and Applications from Université Côte d'Azur. As part of my doctoral studies, I carried out a six-month-long mobility stay with Prof. Sylvain Courrech du Pont in the Laboratoire Matière et Systèmes Complexes in Paris.

It's even better to gaze into a tub of water. To look at water is always good for you and edifying. Even if you can't see anything in it, it's still good. We looked at the water and saw nothing in it, and soon we got bored. But we comforted ourselves that still we had done a good deed. We counted on our fingers. But what were we counting — we didn't know; for is water in any way countable?

– Daniil Kharms

latest news

26 oct 2026	I am happy to participate in the Minisymposium on Drops and bubbles dynamics, capillarity, wetting and non-wetting phenomena at this year’s Journées de la Matière Condensée (Toulouse, 26-30 October), where I will speak about drops sliding down liquid-infused surfaces. Find our abstract here.
15 oct 2026	Our manuscript “Thin-film drainage becomes singular at saddles” has been published in the Physical Review Letters.

selected publications

Thin-film drainage becomes singular at saddles

Simeon Djambov, Alice Marcotte, François Gallaire, and Pier Giuseppe Ledda

Physical Review Letters 137, 2026

Abs DOI PDF Supp arXiv Bib

From coating curved parts to creeping lava, thin-film gravitational drainage over complex surfaces can produce abrupt accumulation, usually associated with sharp edges or defects. Here, experiments, simulations and asymptotics show that a smooth saddle alone generates a logarithmically singular ridge, regularized within a dynamic region where drainage balances hydrostatic pressure and capillarity. In a Newtonian lubrication picture, this mechanism can inform redistribution in manufacturing and geophysics, motivating extensions to complex rheology and interacting geometric features.
@article{djambov2026thinfilm, title = {Thin-film drainage becomes singular at saddles}, author = {Djambov, Simeon and Marcotte, Alice and Gallaire, Fran{\c{c}}ois and Ledda, Pier Giuseppe}, journal = {Physical Review Letters}, volume = {137}, pages = {164002}, year = {2026}, doi = {10.1103/6dfx-zb87}, }
Boundary-layer approach to the linear karren instability

Simeon Djambov and François Gallaire

Journal of Fluid Mechanics 977, 2023

Abs DOI PDF Bib

The present paper concerns the linear fate of transverse perturbations in a gravity-driven, thin-film flow over a soluble substrate. We propose a reduced-order model, based on a boundary-layer treatment of the solute transport and a depth-integration of the Stokes equations, using two extended lubrication methodologies found in the literature. We obtain a closed-form dispersion relation, which we compare to a previous, fully resolved analytical investigation (Bertagni and Camporeale, J. Fluid Mech., vol. 913, 2021, A34). The results allow us to distil the essential physical mechanisms behind the instability.
@article{djambov2023boundary, title = {Boundary-layer approach to the linear karren instability}, author = {Djambov, Simeon and Gallaire, Fran{\c{c}}ois}, journal = {Journal of Fluid Mechanics}, volume = {977}, pages = {R3}, year = {2023}, publisher = {Cambridge University Press}, doi = {10.1017/jfm.2023.932}, }