MIXING OF A PASSIVE SCALAR IN MAGNETICALLY FORCED TWO-DIMENSIONAL TURBULENCE
MIXING OF A PASSIVE SCALAR IN MAGNETICALLY FORCED TWO-DIMENSIONAL TURBULENCE
复制标题
磁力二维湍流中被动标量的混合
DOI：
10.1063/1.869326
复制
发表时间：
1997
影响因子：
4.6
通讯作者：
J. Gollub
中科院分区：
文献类型：
--
作者：
Benjamin S. Williams;D. Marteau;J. Gollub
早在35年前，Batchelor就从理论上讨论了弱扩散杂质在湍流中的空间功率谱Eθ（k）。在合理的假设下，包括流体元素的随机应变，Eθ（k）在波数k超过能谱截止值的范围内，预计将标度为k−1，然后在由应变率和扩散率确定的波数处出现扩散尾。多年来的一些实验似乎支持这一结论，而另一些则不支持。我们已经研究了这个问题的实验中的准二维湍流，建立在一个薄的浮力层，电磁迫使由一个阵列的永久磁铁下的细胞。利用粒子图像测速技术建立了速度场的波数截止，并确定了脉动是均匀的、各向同性的。为了研究混合，染料溶液稳定地引入到浮力层的一侧，并且混合的流体被引入到浮力层中。
More than 35 years ago, Batchelor discussed from a theoretical point of view the spatial power spectrum Eθ(k) of a weakly diffusing impurity mixed by a turbulent fluid flow. Under plausible assumptions including the random straining of fluid elements, Eθ(k) is expected to scale as k−1 for a range of wave numbers k beyond the cutoff of the energy spectrum, followed by a diffusive tail at a wave number determined by the rate of strain and the diffusivity. Some experiments over the years appear to support this conclusion, while others do not. We have investigated this issue experimentally in a quasi-two-dimensional turbulent flow, established in a thin buoyant layer that is electromagnetically forced by an array of permanent magnets beneath the cell. The wave number cutoff of the velocity field is established by particle image velocimetry, and the fluctuations are determined to be homogeneous and isotropic. To study mixing, a dye solution is introduced steadily at one side of the buoyant layer, and mixed flu...