Stokes’ law violation and negative drag in active fluids
Giulia Foffano, University of Edinburgh
Active fluids are suspensions of particles that absorb energy from their surroundings or from an internal tank, in order to do work. Main examples can be found in biological contexts and are e.g. bacteria suspensions and the actomyosin solution, that constitutes the cytoskeleton. I will present simulations where a small constant force is applied to a spherical colloid embedded in an active liquid crystal. In the linear regime the dissipative force acting on the particle embedded in a simple fluid is described by Stokes’ law. Here instead we find a strong non-linearity with respect to the size of the probe and, strikingly, a regime where the colloid reaches a steady state of negative drag.