FIG. 7.

(a) Top views of the particle trajectories in trapezoidal, square, and rectangular channels. The transition from one to two focusing bands occurs at higher flow rate in the square channel under the same conditions. (b) First normal stress difference contours in the corresponding channels. (c) Effects of corner angle on normalized gradient of N₁ as an indicator of elastic force. Corners A and B have angles of 50° and 90°, respectively. A circular channel is assumed to have the corner angle of 180°. (d) Direction of elastic force in the first quarter of square cross section. The direction of elastic force in the blue region is always toward the center while in the orange region is in the opposite direction.