Flow Effect Demonstrator is a desktop level, self circulating, visual fluid dynamics demonstration device designed specifically for teaching, research, and industrial design validation. Without the need for large wind tunnels or CFD post-processing, typical phenomena such as laminar flow, turbulence, boundary layer separation, vortex streets, etc. can be observed with the naked eye within 30 seconds when fluid flows through different geometries, and key parameters can be measured in real time. Multiple scenario simulations can be conducted, such as cylinder/wing flow (Karman vortex street), sudden expansion/contraction pipelines (flow separation and reattachment), bends and valves (secondary flow, local resistance), and open channel weir flow (water jump, energy dissipation).