Abstract
New technique visualize streamlines around a body is devloped by use of Collins's streaklines. When a sphere penetrates a free surface of glycerol in a vessel, the sphere surface is coated with a thin layer of the water-laden glycerol. During the subsequent falling-motion in glycerol this layer is progressively stripped from the sphere surface to form the streakline. The streakline has a refractive index different from that of the surrounding glycerol. When an adequate numbers of spheres are released along a line vertical to the gravitational direction, a row of streaklines are formed. After then a test body is fallen in the field. These streaklines move with the surrounding glycerol according as the movement of the test body. For a steady motion the streaklines coincide with the streamlines. Therefore when a photograph is taken for the field, it show the streamlines of the uniform flow past a fixed body at this moment. The application of this technique to visualize streamlines around a solid sphere and a sperical gas-bubble reveals that the solutions for the Oseen equations represent the streamlines most accurately at a low Reynolds number below 0.4.
