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Morphological transitions of flexible Brownian fibers in interaction with viscous flows
In this presentation we discuss the individual dynamics of flexible and Brownian filaments under shear and compression. We use actin filaments as a model system and observe their dynamics in microfluidic flow geometries using fluorescent labelling techniques and microscopic tracking methods. Our experimental results are compared against Brownian dynamics simulations and theoretical models that describe actin filaments as thermal inextensible Euler–Bernoulli beams whose hydrodynamics follow slender-body theory. Theoretical modeling is used to explain different morphological transitions.
Under shear we characterize successive transitions from tumbling to buckling and finally snake turns as a function of an elasto-viscous number. Under compression we reveal the formation of three dimensional helicoidal structures and characterize their formation.
Finally, we attempt at linking the microscopic observations to the macroscopic suspension properties with preliminary measurements of the shear viscosity of dilute suspensions of actin filaments in microfluidic rheometers.