应韦学勇教授邀请，法国国家科学研究中心主任级研究员Philippe Brunet博士将于1月5日下午4点作线上学术报告，欢迎大家观看！

会议时间：2023/01/05 16:00 (GMT+08:00)

Zoom会议：867 7402 9393

会议密码：20230105

报告内容简介

Our situation concerns a suspension of phototactic and heavy-buoyant micro algae. Having the ability to swim toward gradients of light intensity, algae accumulate in the vicinity of a thin laser beam. The resulting concentration profile can be either stationary, or show dynamical regimes involving so-called bio-convection, due to that algae are non-neutrally buoyant. Controlling both the pseudo-Rayleigh number via the suspension depth and initial concentration of microbes, and the laser beam width (see setup Fig. 1-left), we put in evidence various dynamical regimes : radial propagating waves, dendritic-like structures with a well-defined orthoradial wavelength, or budding instability as an unique finger grows and expand far away from the light beam [1,2]. Figure 1-Right show the phase diagram and corresponding regimes. Our study also allowed to quantify the phototactic response of the algae from a population dynamics, which reveals the highly non-linear response of algae with light intensity [2]. 

[1] J. Dervaux, M. Capellazzi Resta and P. Brunet. Nature Physics DOI: 10.1038/NPHYS3926 (2017). [2] A. Ramamonjy, J. Dervaux and P. Brunet. Phys. Rev. Lett. 128, 258101 (2022).

报告人简介

Dr. Philippe Brunet, Directeur de Recherches CNRS, works in hydrodynamics instabilities involving free-surface dynamics, droplet handling with mechanical vibrations or ultrasounds, liquid (non)-spreading on superhydrophobic surfaces, soft matter and collective flows of living suspensions, and has strong knowledge in cleanroom techniques (lithography and functionalisation of surfaces). He has co-authored 59 papers in high level peer-reviewed international journals and collects~2600 citations (H-index=27).