Dependence of turbulent wall-shear stress on the amplitude of spanwise transversal surface waves

2015 ◽  
Vol 119 ◽  
pp. 261-275 ◽  
Author(s):  
S.R. Koh ◽  
P. Meysonnat ◽  
V. Statnikov ◽  
M. Meinke ◽  
W. Schröder
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Surface Waves ◽  
Wall Shear ◽  
Turbulent Wall

Quantifying Turbulent Wall Shear Stress in an Arteriovenous Graft Using Large Eddy Simulation

2012 ◽  
Author(s):  
L. D. Browne ◽  
P. Griffin ◽  
M. T. Walsh
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Large Eddy Simulation ◽  
Secondary Patency ◽  
Arteriovenous Graft ◽  
Venous Anastomosis ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Wall Shear ◽  
Turbulent Wall

Hemodialysis patients require a vascular access capable of accommodating the high blood flow rates required for effective dialysis treatment. The arteriovenous graft is one such access. However, this access type suffers from reduced one year primary & secondary patency rates of 59–90% and 50–82% respectively [1]. The main contributor to the failure of this access is stenosis via the development of intimal hyperplasia (IH) that predominately occurs at the venous anastomosis. It is hypothesized that the resulting transitional to turbulent flow regime within the venous anastomosis contributes to the development of IH. The aim of this study is to investigate the influence of this transitional to turbulent behavior on wall shear stress within the venous anastomosis via the use of large eddy simulation.

Quantifying Turbulent Wall Shear Stress in a Stenosed Pipe Using Large Eddy Simulation

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Roland Gårdhagen ◽  
Jonas Lantz ◽  
Fredrik Carlsson ◽  
Matts Karlsson
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Large Eddy Simulation ◽  
Recirculation Zone ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Large Fluctuations ◽  
Time Average ◽  
Wall Shear ◽  
Turbulent Wall

Large eddy simulation was applied for flow of Re=2000 in a stenosed pipe in order to undertake a thorough investigation of the wall shear stress (WSS) in turbulent flow. A decomposition of the WSS into time averaged and fluctuating components is proposed. It was concluded that a scale resolving technique is required to completely describe the WSS pattern in a subject specific vessel model, since the poststenotic region was dominated by large axial and circumferential fluctuations. Three poststenotic regions of different WSS characteristics were identified. The recirculation zone was subject to a time averaged WSS in the retrograde direction and large fluctuations. After reattachment there was an antegrade shear and smaller fluctuations than in the recirculation zone. At the reattachment the fluctuations were the largest, but no direction dominated over time. Due to symmetry the circumferential time average was always zero. Thus, in a blood vessel, the axial fluctuations would affect endothelial cells in a stretched state, whereas the circumferential fluctuations would act in a relaxed direction.

Measurement of turbulent wall shear-stress using micro-pillars

2013 ◽  
Vol 24 (12) ◽  
pp. 124002 ◽  
Author(s):  
E P Gnanamanickam ◽  
B Nottebrock ◽  
S Große ◽  
J P Sullivan ◽  
W Schröder
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Wall Shear ◽  
Turbulent Wall ◽  
Micro Pillars
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