Pressure drop measurements and calculations were carried out for differently shaped packings of particles (315-1000 mu m) in milli-structured reactors with slit widths of 1.5-3 mm. It could be shown that the wall effect in these packings with D/d ratios between 6 and about 14 must be taken into account while laminar flow dominates for the employed Reynolds numbers in the range 0.5 < Re-epsilon < 12. Although developed for cylindrical packings, earlier proposed pressure drop correlations including wall effect terms can be also applied to slit-type channels. For prediction of pressure drops over packings of non-spherical particles it is recommended to evaluate the results with the volume-equivalent sphere diameter which is corrected by the sphericity instead of the Sauter diameter. An exact prediction of the pressure drop, however, is only possible if the sphericity is used as a fitting parameter. Furthermore-tomographic scans of real packings were used to describe the geometry for pore scale resolving simulations of the flow and pressure drop calculations using the lattice-Boltzmann method. While an excellent agreement between measurements and simulations was achieved for the non-spherical catalyst particles, the simulations slightly overestimated the pressure drop for the glass beads. These deviations are most probably due to artefacts occurring during the binarization procedure of the scans. (C) 2016 Elsevier Ltd. All rights reserved.