Physics and Mathematics Department, Mary State University, Lenin Sq. 1, Yoshkar-Ola 424000, Russia.
J Magn Reson. 2013 May;230:1-9. doi: 10.1016/j.jmr.2013.01.004. Epub 2013 Feb 4.
This article presents a new approximation describing fluid diffusion in porous media. Time dependence of the self-diffusion coefficient D(t) in the permeable porous medium is studied based on the assumption that diffusant molecules move randomly. An analytical expression for time dependence of the self-diffusion coefficient was obtained in the following form: D(t)=(D0-D∞)exp(-D0t/λ)+D∞, where D0 is the self-diffusion coefficient of bulk fluid, D∞ is the asymptotic value of the self-diffusion coefficient in the limit of long time values (t→∞), λ is the characteristic parameter of this porous medium with dimensionality of length. Applicability of the solution obtained to the analysis of experimental data is shown. The possibility of passing to short-time and long-time regimes is discussed.
本文提出了一种新的近似方法来描述多孔介质中的流体扩散。基于扩散分子随机运动的假设，研究了可渗透多孔介质中自扩散系数 D(t)的时间依赖性。自扩散系数随时间的变化的解析表达式为：D(t)=(D0-D∞)exp(-D0t/λ)+D∞，其中 D0 是本体流体的自扩散系数，D∞是长时间极限（t→∞）下自扩散系数的渐近值，λ 是具有长度维度的这种多孔介质的特征参数。展示了所得到的解在分析实验数据中的适用性。讨论了进入短时间和长时间状态的可能性。
