Vortex dynamics play an important role in the transport of mass, momentum, and energy of a flow field. Thus, vortex manipulation is the key for controlling the efficiency of any device involving flow mixing. For example, the fuel-air mixing in a combustion chamber is the primary process governing the combustion efficiency. In this study we visualize and measure the size of vortices behind a flat plate to address vortex formation, size manipulation, distance of the origin of reverse flow from the plate, and response to the change of the Reynolds (Re) number. This study also investigates the physics behind the generation and size manipulation of twin vortices behind a flat plate and the functional dependence of reverse flow location with the Re number.