Ra. Peattie et al., DEVELOPMENT OF TURBULENCE IN STEADY FLOW-THROUGH MODELS OF ABDOMINAL AORTIC-ANEURYSMS, Journal of ultrasound in medicine, 13(6), 1994, pp. 467-472
Citations number
5
Categorie Soggetti
Acoustics,"Radiology,Nuclear Medicine & Medical Imaging
As part of a general examination of the effects of blood flow patterns
on the risk of rupture of abdominal aortic aneurysms, we have investi
gated steady flow through a series of polyvinyl chloride models of fus
iform aneurysms. A series of steady flow rates between 460 ml/min and
2.0 l/min have been delivered through the models, and the resulting fl
ow patterns have been evaluated by color Doppler flow imaging. At low
volume flow rates, the pattern of flow through the model is smooth and
laminar. At higher flow rates, however, this is replaced by an irregu
lar, fluctuating, and apparently turbulent motion. This finding is con
sistent with previous clinical observations. Turbulence appears initia
lly at the distal end of the model aneurysm and then spreads proximall
y to fill the whole model only if the flow rate continues to increase.
The onset of irregular, turbulent flow is found to be governed by bot
h the overall flow rate through the model and the model diameter. Crit
ical conditions for the appearance of turbulence are presented and dis
cussed, and the critical value of the Reynolds number for both the ini
tial distal transition and the final full transition is shown to decre
ase as the size of the model aneurysm increases.