Ermakova Elena A, Shnol Emmanuil E, Panteleev Mikhail A, Butylin Andrey A, Volpert Vitaly, Ataullakhanov Fazoil I
Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, Russia.
PLoS One. 2009;4(2):e4454. doi: 10.1371/journal.pone.0004454. Epub 2009 Feb 12.
Existence of flows and convection is an essential and integral feature of many excitable media with wave propagation modes, such as blood coagulation or bioreactors.
METHODS/RESULTS: Here, propagation of two-dimensional waves is studied in parabolic channel flow of excitable medium of the FitzHugh-Nagumo type. Even if the stream velocity is hundreds of times higher that the wave velocity in motionless medium (), steady propagation of an excitation wave is eventually established. At high stream velocities, the wave does not span the channel from wall to wall, forming isolated excited regions, which we called "restrictons". They are especially easy to observe when the model parameters are close to critical ones, at which waves disappear in still medium. In the subcritical region of parameters, a sufficiently fast stream can result in the survival of excitation moving, as a rule, in the form of "restrictons". For downstream excitation waves, the axial portion of the channel is the most important one in determining their behavior. For upstream waves, the most important region of the channel is the near-wall boundary layers. The roles of transversal diffusion, and of approximate similarity with respect to stream velocity are discussed.
These findings clarify mechanisms of wave propagation and survival in flow.
流动和对流的存在是许多具有波传播模式的可兴奋介质（如血液凝固或生物反应器）的基本且不可或缺的特征。
方法/结果：在此，研究了FitzHugh-Nagumo型可兴奋介质在抛物线形通道流中的二维波传播。即使流体速度比静止介质中的波速高数百倍，最终也会建立起激发波的稳定传播。在高流体速度下，波不会从壁到壁跨越通道，而是形成孤立的激发区域，我们称之为“受限子”。当模型参数接近临界参数时，在静止介质中波会消失，此时受限子尤其容易观察到。在参数的亚临界区域，足够快的流体速度通常会导致以“受限子”形式移动的激发得以存活。对于下游激发波，通道的轴向部分在决定其行为方面最为重要。对于上游波，通道最重要的区域是近壁边界层。讨论了横向扩散以及与流体速度近似相似性的作用。
这些发现阐明了波在流动中传播和存活的机制。
