非费克质量传递的“瞬态薄层”模型

提出了超常质量传递的“瞬态薄层”模型－在超常质量传递条件下，紧靠介质内受质量扰动的位置，存在一“薄层”区域，该薄层内的质量传递必须考虑非费克效应，而在此薄层外，介质内其他部分部分的质量传递仍近似符合费克定律，“薄层”区域边界上的质量传递满足连续性边界条件，文中以受脉冲质量拢动的质量传递过程为例，采用类似于非傅里叶导热方程的双曲线非费克质量传递方程来描述该“薄层”内的的非费克质量传递，并用有限差分结合MacCormack预测－较正法对其进行了数值求解，在分析介质内出现的非费克效应的同时，得出了“瞬态薄层”厚度与介质的质松时间，质扩散率以及质量扰动的强度和瞬时性强弱的相关关系。

Instantaneous Thin layer

An “instantaneous thin layer” model for transnormal mass transfer is brought forward in this paper. In transnormal mass transfer,there is an interface existing in the medium,which divides the object into two parts: the “instantaneous thin layer”,which is a thin layer region around the mass disturbance position,and the other part of the object. Mass transfer in the “thin layer” is governed by non-Fick law, while that in the other part still complies with the Fick's law approximatively. Mass transfer on the boundary surface of the “thin layer” region satisfies the continuous boundary conditions (i.e.the fourth kind of boundary conditions). An example of one-dimensional transnormal mass transfer, resulting from a pulsed mass disturbance source,is presented in this paper,too. The hyperbolic non-Fick mass transfer equation,which is similar to the hyperbolic non-Fourier heat conduction equation,is used to describe this transnormal mass transfer,and the finite difference method(FDM)combined with MacCormack's predictor-corrector schems is used to solve it. Ultimately the correlativity of the thickness of the “instantaneous thin layer” to the mass relaxation time, mass diffusivity and the mass disturbing source is obtained.