Spiral Waves in Driven Dusty Plasma Medium: Generalized Hydrodynamic Fluid Description

Spiral waves are observed in many natural phenomena. They have been extensively represented by the mathematical FitzHugh-Nagumo (FHN) model [Barkley et al., Phys. Rev. A 42, 2489 (1990)] of excitable media. In incompressible fluid simulations also excitation of thermal spiral waves have been reported by Li et al. [Phys. of Fluids 22, 011701 (2010)]. In the present manuscript the spatiotemporal development of spiral waves in the context of weak and strong coupling limits have been shown. While the weakly coupled medium has been represented by a simple fluid description, for the strong coupling a generalized visco - elastic fluid description has been employed. The medium has been driven by an external force in the form of a rotating electric field. It is shown that when the amplitude of force is small the density perturbations in the medium are also small. In this case the excitations do not develop as a spiral wave. Only when the amplitude of force is high so as to drive the density perturbations to nonlinear amplitudes does the spiral density wave formation occur. The role of forcing frequency, the effect of strong coupling and sound velocity of medium on the formation and evolution of spiral waves have been investigated in detail.