Authors discovered a flip-flop flow phenomenon in network ducts of flow through banks of diamond-shape columns and circular tubes. An experimental study was performed to disclose the flow characteristics in newly typed flow networks with which slot-perforated plate bundles in three rows were arranged in different types. The depth of their ducts was as almost same as the relative length of the slot-perforated plate bundles. The flow patterns were visualized by the tracer method and the velocity variations in the flow field were measured using two-dimensional laser Doppler velocimetry. It is disclosed that the difference of vortices occuring in the slot-perforated plate bundles depends on their arrangements.