抄録
The influence of the addition of cationic surfactant (Ethoquard O12) with a concentration of 50ppm on water flow around a cylinder at Reynolds number ReS=64∼600 was investigated by using LDV and PIV. At ReS=300, the flow with the surfactant formed a stagnant zone in front of the cylinder, which appeared periodically and expanding along the axial direction. The period of the appearance was about 120 [s]. The periodical flow structure was visualized by the measuring the velocity fluctuation. The development of the stagnant zone in front of the cylinder induced the expansion of a low speed flow region near the side of the cylinder.
