  The interaction between boundary layer turbulence and a porous layer is the
cornerstone to the interface engineering. In this study, the spatial resolved
transfer entropy is used to assess the asymmetry of the causal interaction next
to a permeable wall. The analysis was based on pore-resolved direct numerical
simulation of turbulent channel flow over a cylinder array. The spatial map of
transfer entropy reveals the information flux between the porous medium and
arbitrary nearby position.
