14:55

15:10

Małgorzata Przerwa

Physics of marine snow coagulation

Faculty of Physics, University of Warsaw

In this talk, I will talk about the phenomenon called "marine snow"; a downstream current of organic sediments, that greatly contribute to the global carbon cycle. As its falling down, it is gathering smaller particles, changing its size and velocity. We have constructed a theoretical model to describe the impact of a marine snow particle coagulating with smaller particles on its velocity and growth and then changed it slightly to see the changes. We then numerically solved it for a couple of chosen parameter pairs. Our results seem to be in agreement with the experimental data on the level of the size and reached depth. We will list a couple of ways one can further improve this theoretical model.

15:10

15:25

Karol Makuch

Diffusion and Flow in Complex Liquids

Institute of Physical Chemistry, Polish Academy of Sciences

Describing diffusion in complex liquids is challenging due to the numerous interactions between particles and the intricate structure of the medium. This complexity hinders the development of accurate models for predicting diffusion behavior. In this study, we investigate the potential of using a viscosity function to construct a robust theoretical framework for diffusion in complex liquids.

15:25

15:40

Giulio Facchini

Phyllotactic structures in reactive spatial symmetry-breaking systems

Laboratoire Matière et Systèmes Complexes Paris

Phyllotactic patterns, i.e. regular arrangements of leaves or flowers around a plant stem, are beautiful and fascinating examples of complex structures encountered in Nature. In botany, their peculiar symmetries develop when a new primordium periodically grows in the largest gap left between the previous primordium and the apex. Experiments using ferrofluids droplets have also shown that phyllotactic patterns spontaneously form when identical elements repulsing each other are periodically released at a given distance from an injection centre and are advected radially at a constant speed.

More recently, we did observe analogous spiralling patterns in the context of precipitation experiments obtained by radial injection in a confined geometry. Inspired by those experiments, we show here that classical models of phase separation and Turing patterns do also produce spiralling patterns when coupled to a radial injection dynamic. Our results suggest that these models are part of a larger family of self-organised phyllotactic structures, which originate when a spatial symmetry-breaking system giving spotted structures with an intrinsic wavelength is coupled to radial growth.

15:40

15:55

Soheil Arbabi

Molecular Dynamics Simulation of the Coalescence of Freely Suspended and Sessile Droplets

Institute of Physics, Polish Academy of Sciences

Droplet coalescence is commonly encountered in nature and is also relevant in various technologies, such as microfluidics. I will present our results on the coalescence of surfactant-laden water droplets, which have been obtained using molecular dynamics simulations of a coarse-grained force field. In particular, I will discuss the details of the coalescence mechanism and the dynamics of bridge growth and mass transport during the coalescence of freely suspended droplets and sessile droplets.