A numerical investigation has been carried out to study the effect of the sidewalls and the number of cells in arrays of spacer-filled channels on the local flow distribution, for Reynolds number, Re = 100, for a spacer-configuration typically employed in process industries. It was found that the channel sidewalls have a significant effect on the velocity profile near the walls. Numerically calculated values of velocity are compared with those measured experimentally, with good agreement being obtained; a maximum deviation of 4.5% was observed. Particle traces emitted from a cell at the channel entrance revealed that, unexpectedly, the flow moves parallel to the spacer filaments within each channel layer and changes 90 degrees direction mostly at the cell adjacent to the channel side walls. The effects of the number of cells and the type of boundary condition imposed on the channel transverse sidewalls on the pressure drop and friction factor are considered. ; peer reviewed: yes ; NRC Pub: yes