On the homogenized description of flow and transport through the trabecular network in the subarachnoid space

The pulsating motion of the cerebrospinal fluid in the subarachnoid space (SAS) surrounding the brain and the spinal cord is known to be affected by the presence of trabeculae, which are thin collagen-reinforced fibers that form a dispersed web-like structure stretching across the SAS. Previous analyses have employed a homogenized treatment involving the familiar conservation equations of flow and transport in porous media. The accuracy of the resulting macroscopic equations is tested here through comparisons with direct numerical simulations in which the SAS is modelled as a parallel-plate channel populated by a random distribution of transverse cylindrical posts. The comparisons explore values of the controlling flow parameters in physiologically relevant ranges.