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中国物理学会期刊

双层耦合非对称反应扩散系统中的振荡图灵斑图

CSTR: 32037.14.aps.70.20201710

Oscillatory Turing patterns in two-layered coupled non-symmetric reaction diffusion systems

CSTR: 32037.14.aps.70.20201710
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  • 采用线性耦合Brusselator模型和Lengyel-Epstein模型, 数值研究了双层耦合非对称反应扩散系统中振荡图灵斑图的动力学, 并分析了图灵模、高阶模以及霍普夫模之间的相互作用及其对振荡图灵斑图的影响. 模拟结果表明, 在Lengyel-Epstein模型激发的超临界图灵模 k_1的激励下, Brusselator模型中处于霍普夫区域的高阶模 \sqrt 3 k_1被激发, 这两个模式相互作用从而产生了同步振荡六边形斑图. 随着控制参数b的增加, 该振荡六边形斑图首先经历倍周期分岔进入双倍振荡周期, 经历多倍振荡周期后, 在霍普夫模式的参与下, 最终进入时空混沌态. 同步振荡六边形斑图形成的条件是Brusselator模型中的次临界图灵模 k_2的本征值高度低于处于霍普夫区域的高阶图灵模 \sqrt 3 k_1的本征值高度, 且两个图灵模之间不存在空间共振关系. 当两个图灵模满足空间共振时, 系统优先选择空间共振模式, 从而产生超点阵斑图. 霍普夫模和图灵模共同作用下只能产生非同步振荡图灵斑图. 此外, 耦合强度对振荡图灵斑图也有重要的影响.

     

    Pattern formation and self-organization are ubiquitous in nature and commonly observed in spatially extended non-equilibrium systems. As is well known, the origin of spatio-temporal patterns can be traced to the instability of the system, and is always accompanied by a symmetry breaking phenomenon. In reality, most of non-equilibrium systems are constructed by interactions among several different units, each of which has its unique symmetry breaking mechanism. The interaction among different units described by coupled pattern forming system gives rise to a variety of self-organized patterns including stationary and/or oscillatory patterns. In this paper, the dynamics of oscillatory Turing patterns in two-layered coupled non-symmetric reaction diffusion systems are numerically investigated by linearly coupling the Brusselator model and the Lengyel-Epstein model. The interaction among the Turing modes, higher-order harmonics and Hopf mode, and their effects on oscillatory Turing pattern are also analyzed. It is shown that the supercritical Turing mode k_1 in the Lengyel-Epstein model is excited and interacts with the higher-order harmonics \sqrt 3 k_1 located in the Hopf region in the Brusselator model, and thus giving rise to the synchronous oscillatory hexagon pattern. The harmonic \sqrt 2 k_1 that can also be excited initially is some parameter domain, but it is unstable and vanishes finally. As the parameter b is increased, this oscillatory hexagon pattern first undergoes period-doubling bifurcation and transits into two-period oscillation, and then into multiple-period oscillation. When the Hopf mode participates in the interaction, the pattern will eventually transit into chaos. The synchronous oscillatory hexagon pattern can only be obtained when the subcritical Turing mode k_2 in the Brusselator model is weaker than the higher-order harmonics \sqrt 3 k_1 located in the Hopf region and neither of the two Turing modes satisfies the spatial resonance condition. The system favorites the spatial resonance and selects the super-lattice patterns when these modes interact with each other. The interaction between Hopf mode and Turing mode can only give rise to non-synchronous oscillatory patterns. Moreover, the coupling strength also has an important effect on the oscillatory Turing pattern. These results not only provide a new pattern forming mechanism which can be extended to other nonlinear systems, but also gives an opportunity for more in-depth understanding the nature and their relevance to technological applications.

     

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