Experimental analysis of unsteady flows through a stenosis.

In this paper we present a study of the post-stenotic velocity flow field corresponding to oscillatory, pulsatile and physiological flow waveforms. Two-dimensional velocity measurements are performed in a 75% severity stenosis using a pulsed Doppler ultrasonic velocimeter. Emphasis is placed on the analysis of the experimental velocity-profile patterns. It is recognized that, beyond the influence of the flow parameters such as the Reynolds number and the frequency parameter, velocity profiles (hence wall-shear stresses) highly depend on the flow waveform. In addition to this analysis, a model of the stenosis influence length is proposed in the case of oscillatory flow.