3D conformation of a flexible fiber in a turbulent flow

A growing number of studies is devoted to anisotropic particles in turbulent flows. In most cases, the particles are assumed to be rigid and their deformations are neglected. We present an adaptation of classical computer vision tools to reconstruct from two different images the 3D conformation of a fiber distorted by the turbulent fluctuations in a von Karman flow. This technique allows us notably to characterize the fiber deformation by computing the correlation function of the orientation of the tangent vector. This function allows us to tackle the analogy between polymers and flexible fibers proposed by Brouzet et al. (Phys Rev Lett 112(7): 074501, 2014). We show that this function depends on an elastic length l(e) which characterizes the particle flexibility, as is the case for polymers, but also on the fiber length L, contrary to polymers.