This paper focuses on the investigation of the wake flow around a circular patch of cylinders with different solid volume fractions (SVF). The wake flow pattern was found to be dependent on the SVF and the flow stability factor S. A non-hydrostatic model was used to simulate the open channel flow through the cylinders. The turbulence was simulated using the SST (shear strain transport) k-ω turbulence model. The model was first validated against experimental data to ensure the accuracy of the numerical simulation. Then the local turbulent flow and the wake flow field structures were investigated by changing the SVF and the water depth. The spatial evolution of the wake flow behind the patch was analysed, and the correlation between the flow pattern and the wake flow stability was discussed. The cylinder-scale turbulence was intensive, even at low SVFs and low water depths. In contrast, the patch-scale turbulence in the wake was suppressed and the unsteady bubble wake was formed when the water depth decreased, which revealed the importance of the bed friction force to the flow pattern. The parameters S and SVF were adjusted to demonstrate their contributions to the formation of the different wake flow patterns.