Perforated plates are used in many applications such as electrostatic precipitators in environmental control systems as a method of fluid flow control. The detailed structure of perforated plates causes difficulties in the design and optimization of systems by mathematical modelling. Hence, a simplified model for the perforated plates is important. In the current work, numerical experiments based on Computational Fluid Dynamics (CFD) are carried out at a microscopic, unit cell scale. The effects of a series of parameters on the flow pattern and pressure loss are investigated, including Reynolds number, open porosity, orifice diameter, plate thickness, surface roughness and plate inclination angle. Good agreement is observed between the current predictions and empirical equations/experimental data in the literature. The pressure loss is found to be determined by the large flow structures in the expansion behind the plate. The results can be potentially used for the modelling of flow distribution in electrostatic precipitators in particular.