Flow through S-shaped glass models simulating arterial tortuosities.

Flow patterns in twenty-one glass models of S bends were examined using the dye-injection technique. The glass models were of different configurations designed to simulate arterial tortuosities. In each model flow disturbances were observed in the stem distal to the S bend or in the distal portion of the S bend itself at Reynolds numbers below 2000. The disturbances were periodic in nature and mostly regular, but with considerable sensitivity to external disturbances. The sharpness of the flexures appeared to be important in determining the Reynolds number at which flow disturbances occurred. The significance of the flow disturbances is their seeming applicability to the human vascular system.