Active and passive control of spiral turbulence in excitable media.pdf

Active and passive control of spiral turbulence in excitable media Guoning Tang,1 Minyi Deng,1 Bambi Hu,2 and Gang Hu3,4,* 1College of Physics and Electronic Engineering, Guangxi Normal University, Guilin 541004, China 2Department of Physics and Center for Nonlinear Studies, Hong Kong Baptist University, Hong Kong, China 3Department of Physics, Beijing Normal University, Beijing 100875, China 4Beijing–Hong Kong–Singapore Joint Center of Nonlinear and Complex Systems, Beijing Normal University Branch, Beijing, China
Received 29 April 2007; revised manuscript received 8 October 2007; published 23 April 2008 The influence of a spatially localized heterogeneity defect, defined by failure of the diffusion effect, on spiral turbulence suppression in two-dimensional excitable media is studied numerically, based on the B?r model. It is shown that in certain parameter regions spiral turbulence without the defect can be suppressed by a boundary periodic forcing
called active control if the forcing frequency is properly chosen. However, with a sufficiently large defect this active control method no longer works due to the wake turbulence following the defect. We suggest an auxiliary method of enclosing the defect with a thin layer of material of high excitability
called passive control to screen the interaction between the defect and the turbulence and to restore the global control effect of the periodic forcing. The possible application of the method in cardiac defibrillation is discussed. DOI: 10.1103/PhysRevE.77.046217 PACS number
s: 05.45.
a, 82.40.Ck, 82.20.
w I. INTRODUCTION Excitable media are extended spatial systems that support propagation of waves including pulses and rotating spirals. Thus various models of excitable media have been used to account for nonlinear wave phenomena in many fields of biology, chemistry, and physics 1. Wave propagation in in- homogeneous media has attracted much attention in the past decades because some natural reaction-diffusio