Abstract: The present invention refers to a unit for viewing the time-dependent fluid flow restart, comprising two hydraulically connected reservoir tanks (1, 2); two auxiliary pipes (3); a main pipe (4) between the reservoir tanks (1, 2) and between the auxiliary pipes (3); a viewing box (15); a pressurization system (20); data acquisition software; and a particle image velocimetry (PIV) system (8); wherein the main pipe (4) is made of a transparent acrylic material that allows the viewing of the fluid inside the same; wherein the viewing box (15) encompasses the main pipe (4) and allows its viewing; and wherein the unit views the restart of the time-dependent fluid flow in transient regime.