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Model studies of the closing behaviour of the aortic valve

The closing mechanism of the natural aortic valve is investigated experimentally in a two-dimensional analogue. The interaction between the sinus content and the aortic flow when the latter is decelerating is studied for different Strouhal numbers: for high Strouhal numbers the sinus content rotates virtually as a rigid mass around the centreline whereas for low Strouhal numbers, corresponding to the human situation, the cusp remains straight and slowly rotates around its point of attachment. Simple theoretical models based on the phenomena observed are proposed. Acceptable agreement between theory and experiment is found.