New approaches to the modeling of microtubule-based active nematics

Title: New approaches to the modeling of microtubule-based active nematics

Abstract: Microtubule-based active nematics are often modeled using a continuum
theory for the Q-tensor (describing the order and orientation of the
nematic phase) and the fluid velocity u.  This theory consists of a
nematic transport equation for Q and the Navier-Stokes equation for u.
Central to both of these equations is a free energy functional
depending on the Q-tensor, which is typically taken to be of the
Landau-deGennes form.  After reviewing the standard formalism, we
propose two significant modifications that aim to more accurately
capture the underlying physics.  The first involves what we call the
"nematic locking principle", the idea that an individual microtubule
bundle is simply advected by the fluid flow.  The second modification
aims to capture (potentially large) density variations in the material,
reproducing the striation patterns typically seen in experiments.