Defect dynamics in viscoelastic passive and active nematics

Passive and active nematics are most often modeled as ordered fluids. However, in biopolymeric systems, elastic stresses can play an important role in shaping the evolution of the nematic field and material flows. Here, we explore a hydrodynamic model of nematics that includes a single relaxation time through linear stability analysis and simulation. We find that stress build-up during defect motion impacts their annihilation dynamics. Results are discussed in the context of experimental work on microtubule-based active nematics and passive biomolecular condensates.