Abstract: The stability of circular cylinder wake at low Reynolds numbers has been studied experimently. The experiments were separatly carried out in a propeller-driven water channel and in a gravity-driven low turbulence water tunnel. The test section of water channel was 15 cm in width, 10cm in depth and 100 cm in length, and the test section of water tunnel was 4 cm in width.10cm in height and 100 cm in length. The cylinder model used in channel and tunnel were 15 cm long, 0.2 cm in diameter and 4cm long, 1 cm in...