[Seminar] An introduction to self-similarity of the first and second kind

Speaker: Dr. Shreyas Mandre

University Associate Professor of Fluid-Structure Interaction, Department of Engineering, University of Cambridge

Hosted by: Professor Mahesh Bandi, Nonlinear and Non-equilibrium Physics Unit

When physical processes repeat over either growing or shrinking scales (length and/or time), the dynamics shows self-similarity. The condition of self-similarity appears strict, but it is the building block of mathematical modelling. This lecture covers (i) concept of scale invariance as a pre-requisite for self-similarity, (ii) self-similarity in physical systems and mathematical models, (iii) the two kinds of self-similarity -- the first and second kinds, and (iv) a simple mathematical example to elucidate the second kind of self-similarity. The lecture presents examples from fluid dynamics. No previous knowledge of or experience with scale-invariance or self-similarity is assumed.

Current Advances in Turbulence and multiphase flowS - 24CATS

OIST Workshop | Website | Main organizer: Marco Edoardo Rosti (Complex Fluids and Flows Unit) | OIST members are welcome to attend all scientific sessions. Meals are closed sessions for registered participants.

[Seminar] Flows and Topological Changes During Tissue Morphogenesis

Speaker: Professor Luiza Angheluta-Bauer, Condensed Matter Physics, University of Oslo

Hosted by Professor Mahesh Bandi Nonlinear and Non-equilibrium Physics Unit

Abstract:

Collective structural arrangements and cell migration are important physical processes underlying tissue development and regeneration. Understanding the complexity of cell-cell interactions and the emergence of collective behaviors at the tissue scale presents formidable challenges both experimentally and theoretically.

In this talk, I will discuss recent theoretical work on the dynamical patterns that emerge at the tissue scale from localized rearrangements and topological defects. Using a multi-phase field model, we demonstrate that tissue fluidity stems from cell neighbor exchanges, serving as transient sources of vortical flow. This flow emerges from the relative dispersion of cells at a rate proportional to the frequency of rearrangements. Balancing collective migration with relative cell motion appears to be essential for maintaining tissue shape and fluidity. Using a cell-based model, we study the tissue's response to the presence of a vortex. While solid-like behavior tends toward conical shapes, localized fluidization triggers the transition to a tube, which is fundamental in biological tissues.