Abstract
Accurate evaluation of turbulent velocity statistics in pulsatile flows is important in estimating potential damage to blood constituents from prosthetic heart valves. Variations in the mean flow from one cycle to the next can result in artificially high estimates. Here we demonstrate a procedure using a digital, low-pass filter to remove the cycle-to-cycle variation from turbulence statistics. The results show that cycle-to-cycle variations can significantly affect estimates of turbulent Reynolds stress and should be either eliminated or demonstrated to be small when reporting pulsatile flow results.
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Abbreviations
- D :
-
inside diameter of aortic valve
- R :
-
radius of model aorta
- Δt :
-
time window
- t :
-
time
- T :
-
period of cycle
- T′ :
-
duration of outflow pulse from ventricle
- U :
-
instantaneous axial velocity
- U L :
-
low-pass axial velocity
- U p :
-
mean periodic axial velocity
- 〈U〉:
-
ensemble averaged axial velocity
- 〈uv〉:
-
ensemble-average turbulent velocity product
- 〈u′〉:
-
root-mean-square of turbulent axial velocity
- 〈U max〉:
-
maximum, ensemble-averaged axial velocity
- V :
-
instantaneous radial velocity
- y :
-
vertical distance from aorta centerline
- z :
-
axial distance downstream of prosthetic heart valve
References
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Tiederman, W.G., Privette, R.M. & Phillips, W.M. Cycle-to-cycle variation effects on turbulent shear stress measurements in pulsatile flows. Experiments in Fluids 6, 265–272 (1988). https://doi.org/10.1007/BF00187366
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DOI: https://doi.org/10.1007/BF00187366