Turbulent velocity measurements in a model of aortic stenosis

Abstract

Experimental results from a laboratory model of aortic stenosis are presented. Valves were represented by a number of nozzles, using three area ratios for varying degrees of stenosis severity, and including non-symmetrical shapes. Steady flow tests were run for a range of Reynolds numbers (Re) appropriate to aortic flow. Turbulence intensities downstream of the nozzle were measured in both axial and radial directions, together with profiles of time mean velocity. The maximum normalised intensity was found to be independent of Re (based on nozzle diameter) for values >9000. Non-dimensional power spectra of the maximum intensity showed some Re dependence but were almost independent of nozzle area ratio and shape, except for oblique nozzles. The spectrum shape depended upon radial and axial positon near the stenosis but by six “aorta” diameters downstream the turbulence was almost homogeneous. The spectrum from a pulsatile flow test was very similar to the corresponding steady flow case.