Alexakis A, Mininni P D, Pouquet A
NCAR, Boulder, Colorado 80307-3000, USA.
Phys Rev Lett. 2005 Dec 31;95(26):264503. doi: 10.1103/PhysRevLett.95.264503. Epub 2005 Dec 23.
We investigate the locality of interactions in hydrodynamic turbulence using data from a direct numerical simulation on a grid of 1024(3) points; the flow is forced with the Taylor-Green vortex. An inertial range for the energy is obtained in which the flux is constant and the spectrum follows an approximate Kolmogorov law. Nonlinear triadic interactions are dominated by their nonlocal components, involving widely separated scales. The resulting nonlinear transfer itself is local at each scale but the step in the energy cascade is independent of that scale and directly related to the integral scale of the flow. Interactions with large scales represent 20% of the total energy flux. Possible explanations for the deviation from self-similar models, the link between these findings and intermittency, and their consequences for modeling of turbulent flows are briefly discussed.
我们使用在1024(3)点网格上的直接数值模拟数据，研究了流体动力学湍流中相互作用的局域性；流动由泰勒-格林涡驱动。得到了一个能量惯性范围，其中通量是恒定的，谱遵循近似的柯尔莫哥洛夫定律。非线性三元相互作用由其非局域分量主导，涉及广泛分离的尺度。由此产生的非线性传递在每个尺度上本身是局域的，但能量级联中的步长与该尺度无关，且与流动的积分尺度直接相关。与大尺度的相互作用占总能量通量的20%。简要讨论了与自相似模型偏差的可能解释、这些发现与间歇性之间的联系及其对湍流建模的影响。
