Numerical simulation on the permeability variations of a fiber assembly

Abstract Finite element simulations on permeability variations of an aligned fiber assembly have been conducted. Two dimensional viscous flow in longitudinal and transverse directions has been studied respectively, using the steady state Navier‐Stokes equation but with small Reynolds numbers. Two groups of packing structures are investigated, both with introduced disturbances in the fiber assembly. One is the idealized packings, including hexagonal and square packings, but with selected fibers removed randomly, and with fiber center positions disturbed randomly. This gives random effect within the modeled cells, but on the macro‐scale the structure is still periodic. Numerical simulations are performed using available finite element packages. The result shows clearly that different physical mechanisms doninate the flow process in longitudinal and transverse permeabilities in the longitudinal flow case, the disturbance introduces openings within the bundle, and these openings become between fibers. Thus flow resistance increases substantially in the idealized packing cases. Numerical data are then compared with available data from other studies, particularly that from using self‐consistent methods.