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# Tortuosity of hierarchical porous materials: Diffusion experiments and random walk simulations

*Chemical Engineering Science* Số , năm 2022 (Tập 264, trang -)

**ISSN:** 92509

**ISSN:** 92509

**DOI:** 10.1016/j.ces.2022.118136

**Tài liệu thuộc danh mục:**

Article

English

*Diffusion in liquids; Maxwell equations; Mean field theory; Porous materials; Random processes; Conductivity; Diffusion experiments; Effective media theory; Hierarchical porous; Mean-square displacement; Mesoscopic simulation; Random Walk; Random walk simulation; Theory calculation; Tortuosity; Silica*

**Từ khóa:**Tóm tắt tiếng anh

Diffusion experiments, effective medium theory calculations and random walk simulations were carried out on hierarchical porous materials. The main throughput of the mesoscopic simulations proposed here is the tortuosity defined as the ratio of the fluid mean square displacements calculated in absence and in presence of the porous medium. This is a well-defined definition that has the advantage to be comparable to the ratio of self-diffusion coefficients for the bulk and confined fluid. Such tortuosity can also be compared with the ratio of bulk and effective electrical conductivities. These calculations are applied to hierarchical materials such as those encountered in chromatography, membrane science or catalysis. The simulation results are compared to experimental data as well as to effective equations (Maxwell) which are often invoked to infer tortuosity expressions based on effective mean field theories. The different methods show that the apparent tortuosity versus probe size/pore size ratio display a maximum. � 2022 Elsevier Ltd