“…Heterogeneity along the direction vertical to the flow (Shen and Reible, 2015;Song et al, 2015;Wu et al, 2016;Afshari et al, 2018;Gao et al, 2018;Swami et al, 2018;Li et al, 2019;Kaffel, 2019;Nijjer et al, 2019;Liu W. C., 2020;Ma et al, 2021;Shen et al, 2022), different from the heterogeneity along the flow direction (Liu et al, 2022), is a critical feature of the porous media in the real world. For example, the vertically stratified oil reservoirs (Song et al, 2015;Gao et al, 2018) with vertical permeability heterogeneity are commonly encountered in petroleum engineering, the contaminant transport (Shen et al, 2015;Swami et al, 2018) in vertically layered formations is frequently involved in environment engineering, and the rainfall infiltration into layered soils (Wu et al, 2016;Afshari et al, 2018;Kaffel, 2019;Nijjer et al, 2019) is very common in municipal engineering. Although the research area on the mass transfer through heterogeneous porous media is very challenging due to the involvement of the nonlinear flow process and complex flow situations in the actual engineering background, abundant research on the seepage flow problems in multi-layer porous media considering the heterogeneity has been carried out in recent years.…”