Group of Nonlinear Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
Phys Rev Lett. 2013 Feb 22;110(8):088302. doi: 10.1103/PhysRevLett.110.088302. Epub 2013 Feb 20.
In the absence of advection, reaction-diffusion systems are able to organize into spatiotemporal patterns, in particular spiral and target waves. Whenever advection is present that can be parametrized in terms of effective or turbulent diffusion D(), these patterns should be attainable on a much greater, boosted length scale. However, so far, experimental evidence of these boosted patterns in a turbulent flow was lacking. Here, we report the first experimental observation of boosted target and spiral patterns in an excitable chemical reaction in a quasi-two-dimensional turbulent flow. The wave patterns observed are ~50 times larger than in the case of molecular diffusion only. We vary the turbulent diffusion coefficient D() of the flow and find that the fundamental Fisher-Kolmogorov-Petrovsky-Piskunov equation, v(f) proportional sqrt[D()], for the asymptotic speed of a reactive wave remains valid. However, not all measures of the boosted wave scale with D() as expected from molecular diffusion, since the wave fronts turn out to be highly filamentous.
在没有平流的情况下，反应扩散系统能够形成时空模式，特别是螺旋波和靶波。只要存在平流，可以用有效或湍流扩散 D()来参数化，这些模式应该可以在更大的、增强的尺度上实现。然而，到目前为止，在湍流中还缺乏这些增强模式的实验证据。在这里，我们首次报告了在准二维湍流中的激活动力学反应中观察到的增强的靶波和螺旋波的实验结果。观察到的波模式比只有分子扩散时大约 50 倍。我们改变了流动的湍流扩散系数 D()，并发现对于反应波的渐近速度的基本费希尔-柯尔莫戈罗夫-彼得罗夫斯基-皮斯昆诺夫方程，v(f)正比于 sqrt[D()]仍然有效。然而，并非所有增强波的尺度都与分子扩散所预期的 D()一样，因为波前呈现出高度丝状。
