Webinar

An important class of microscale fluid-structure interactions in biology involves the interactions and deformations of flexible elastica, both passive and active, with fluid flows. This is evident from fundamental biological transport processes such as the swimming microorganisms using internally actuated cilia or flagella, the transport of material by the coordinated action of ciliary carpets, and the involvement of both actuated and passive flexible filaments in the first symmetry-breaking of vertebrate cells. Both single filaments, and assemblies, are challenging to study because individual filaments have many internal degrees of freedom in deformation and can exhibit microscopic instabilities. The interaction of many filaments in these assemblies can be manifested as macroscopic emergent behavior. 

I will present a broad overview of these problems and outline my efforts in developing computational methods for such fluid-structure interaction phenomena. I will then discuss two problems concerning the dynamics of passive and active fibers in flows. First, I will talk about the novel buckling instabilities and complex shapes of single actin polymers in simple flows and their importance in the rheology of complex fluids. I will then discuss a biophysical model of a spontaneously beating cilium that incorporates various details of their microscopic physics. Using this model, I will explain how beds of beating cilia organize to translate the nanoscopic activity of internal molecular motors into the large-scale metachronal waves that help in fluid pumping and clearance.