Flow coherence in a bead pack observed using frequency domain modulated gradient nuclear magnetic resonance
Flow coherence in a bead pack observed using frequency domain modulated gradient nuclear magnetic resonance
复制标题
DOI：
10.1063/1.1336810
复制
发表时间：
2001-02-01
影响因子：
4.6
通讯作者：
Codd, SL
中科院分区：
文献类型：
--
作者：
Callaghan, PT;Codd, SL
我们使用基于周期性波形磁场梯度的新核磁共振（NMR）方法来研究多孔介质中流动的时间相关性。频域调制场梯度核磁共振技术直接产生频率相关色散系数，即速度自相关函数的谱密度。我们对在单分散乳胶珠组（直径 50-136 μm）中流动的水和在 10 到 5000 范围内的佩克莱特数下的水流，在垂直于平均流量的方向上进行了色散光谱的测量。我们在与珠子周围流动的反时限相对应的频率处观察到光谱峰值，我们将这种效应归因于珠子周围相干曲折流。这一观察结果与 Maier 最近的计算机模拟非常一致，其中看到了负速度自相关函数瞬态。 (C) 2001 年美国物理研究所。
We have used a new nuclear magnetic resonance (NMR) method based on periodic wave form magnetic field gradients to investigate temporal correlations for flow in porous media. The frequency domain modulated field gradient NMR technique directly yields the frequencydependent-dispersion coefficient, i.e., the spectral density of the velocity autocorrelation function. Our measurements of dispersion spectra have been carried out, in the direction transverse to the mean flow, for water flowing in a monodisperse latex bead pack (diameters 50-136 mum) and at Peclet numbers ranging from 10 to 5000. We observe spectral peaks at a frequency corresponding to the inverse time for flow around a bead, an effect we attribute to coherent meandering flow around the bead. This observation is in close agreement with the recent computer simulations of Maier , in which negative velocity autocorrelation function transients are seen. (C) 2001 American Institute of Physics.