CHARACTERIZATION AND EVOLUTION OF POST-STENOTIC FLOW DISTURBANCES

The evolution of poststenotic flow disturbances was studied using a laser Doppler anemometer for the measurement of velocity along the centerline of a Plexiglas tube. A sinusoidal velocity variation, superimposed upon a forward mean flow, was employed; and the frequency parameter and peak Reynolds number approximated values typical of the dog aorta. Contoured stenoses of 25, 50 and 75% reduction in cross-sectional area were studied. Results demonstrate the presence of three types of flow disturbance: a coherent structure associated with the initiation of each flow cycle; a periodic disturbance arising from the shear layer distal to the constriction; and nonstationary turbulence. Data analysis methods which allow accurate classification of disturbances are presented. The coherent ″starting structure″ may have relevance in reducing the threshold of recognition of developing atherosclerotic plaques.