On the Validity of the Fick's Law for Multi-component Diffusion

摘要

In this work, a simple methodology to test the validity of the Fick's law is developed by proposing additional restrictions for the Fickian multi-component diffusion coefficients. These restrictions are based on the consideration of the Onsager Reciprocal Relations along with second thermodynamic law constraints and the phase stability criteria. Moreover, it is shown that these additional restrictions could explain in certain cases the discrepancy, reported in the literature, of calculating negative concentrations in Fickian multi-component diffusion observed even if the second thermodynamic law constraints and the phase stability criteria are satisfied. It is believed that this work could be used to further investigate existing theoretical problems such as obtaining physically acceptable mathematical solutions for the multi-component diffusion problem.