Physics and Mathematics Department, Mary State University, Lenin sq., 1, Yoshkar-Ola 424000, Russia.
J Magn Reson. 2012 Mar;216:192-6. doi: 10.1016/j.jmr.2012.01.020. Epub 2012 Feb 8.
A new method of finding experimental time dependence of the self-diffusion coefficient D(t) for fluid in the porous media is proposed. We investigate the time-dependent self-diffusion coefficient D(t) of random walkers in permeable porous media. D(t) is measured in pulse field gradient (PFG) experiments with fluid-saturated porous media of randomly packed spherical glass beads. In absence of the specific interactions between pore walls and a fluid we show that D(t) = (D(0) - D(∞))exp(-F√(D(0)t)/d) + D(∞), where D(0) is the diffusion constant in a bulk fluid, D(∞) is the asymptotical value of the diffusion coefficient for long diffusion times (t→∞), d is the bead diameter and F is the constant characterizing the geometry (the size and shape) pores.
提出了一种新的方法来寻找多孔介质中自扩散系数 D(t) 的实验时间依赖性。我们研究了在可渗透多孔介质中随机行走者的时间相关自扩散系数 D(t)。在具有随机填充的球形玻璃珠的饱和多孔介质的脉冲场梯度 (PFG) 实验中测量 D(t)。在没有孔壁和流体之间的特定相互作用的情况下，我们表明 D(t) = (D(0) - D(∞))exp(-F√(D(0)t)/d) + D(∞)，其中 D(0)是在本体流体中的扩散常数，D(∞)是扩散系数的渐近值对于长时间扩散 (t→∞)，d 是珠的直径，F 是表征几何形状 (大小和形状) 孔的常数。
