Effect of stenotic geometry on flow behaviour across stenotic models

  • U. Solzbach
  • H. Wollschläger
  • A. Zeiher
  • H. Just
Biomechanics

Abstract

In the study the influence of the geometry of stenoses on poststenotic flow characteristics such as faminar flow, separation, flow instabilities and local turbulences were assessed. Stenoses were represented by 12 rigid-walled models. The different geometric characteristics were length, percentage lumen area reduction, exit angle and eccentric location of the residual lumen. The flow characteristics were investigated by visualising the flow pattern with a birefringent solution and by measuring the flow and the pressure drop along the stenoses. All data were obtained under steady flow conditions for Reynolds numbers varying from approximately 1 to 500. In stenoses with short and concentric shapes local turbulence develops at Reynolds numbers well below the corresponding Reynolds numbers obtained in stenoses with the same percent lumen area reduction but with a long and eccentric shape. The results indicate that the photoelastic technique is a suitable method of obtaining a picture of the overall flow field downstream of a constriction.

Keywords

Haemodynamics Rheology Stenotic models 

List of symbols

A, A′

amplitude of the ordinary and extraordinary beam at the photoelastic apparatus

d

diameter of stenosis

D

diameter of unobstructed tube=21 mm

l

distance between pressure taps

L

length of stenosis

ΔP

pressure drop

Re

Reynolds number=2DU ρ/μ

Re*

critical Reynolds number

s

difference between the ordinary and extraordinary beam leaving the test section at the photoelastic apparatus

U

mean velocity in unobstructed tube

Z

axial position from the exit of the stenosis

α

alpha parameter = (D/2)·√2πvρ/μ

β

exit angle of stenosis

γ, γ′

orientation of the principal crystal axes

μ

absolute viscosity of fluid

ν

pulsation frequency

ρ

density of fluid

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Copyright information

© IFMBE 1987

Authors and Affiliations

  • U. Solzbach
    • 1
  • H. Wollschläger
    • 1
  • A. Zeiher
    • 1
  • H. Just
    • 1
  1. 1.Medizinische Universitätsklinik, Abt. 3-KardiologieUniversität FreiburgFreiburgFederal Republic of Germany

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