Hydrodynamic flow in U-shaped and coiled glass loops simulating carotid arterial configurations

The dye injection technique was used to study flow patterns in ten U-bends and two helical coils. These models were manufactured of glass and designed to simulate abnormal arterial configurations in man. In each model flow disturbances were observed below the critical Reynolds number of 2000 for flow in a straight tube with one reading as low as 250. The disturbances in the flow were sensitive to external disturbances. Their periodicity was relatively regular but the frequency increased with augmentation of flow rates and some irregularity was apparent. The results indicate that they could have applicability to the human vascular system.