Seminarium "Modeling of Complex Systems"

Despite significant progress in understanding the behaviour of active fluids, much less is known about how activity affects the behaviour of solid and viscoelastic materials, such as epithelial tissues or biofilms. In this talk, we will show that a viscoelastic thin sheet is driven out of equilibrium by active structural remodelling (e.g., fast growth) develops a wide variety of shapes as a result of a competition between viscous relaxation and activity. In the regime where active processes are faster than viscoelastic relaxation, shapes that are formed due to remodelling are inherently out of equilibrium. The latter regime is of particular interest in developing a physical understanding of morphogenesis, where the embryo has to undergo a series of carefully orchestrated shape changes to establish the functioning organism. Our study suggests that keeping a growing system out of equilibrium increases the range of available morphologies. These observations point to a robust mechanism by which a system that is kept out of equilibrium could be steered toward the desired shape by chemical regulation of remodelling, relaxation, and mechanical parameters.