Journal
PHYSICS OF FLUIDS
Volume 24, Issue 3, Pages -Publisher
AMER INST PHYSICS
DOI: 10.1063/1.3694526
Keywords
-
Categories
Funding
- EPSRC [EP/C539842/1, WT 088641/Z/09/Z]
- British Heart Foundation (BHF) [FS/09/030/27812]
- Centre of Excellence in Medical Engineering
- Wellcome Trust
- BHF Centre of Research Excellence at Imperial College London
- British Heart Foundation [FS/09/030/27812] Funding Source: researchfish
- Engineering and Physical Sciences Research Council [EP/C539842/1, EP/G069581/1] Funding Source: researchfish
- EPSRC [EP/C539842/1, EP/G069581/1] Funding Source: UKRI
Ask authors/readers for more resources
Three-dimensional simulations of blood flow usually produce such large quantities of data that they are unlikely to be of clinical use unless methods are available to simplify our understanding of the flow dynamics. We present a new method to investigate the mechanisms by which vascular curvature and torsion affect blood flow, and we apply it to the steady-state flow in single bends, helices, double bends, and a rabbit thoracic aorta based on image data. By calculating forces and accelerations in an orthogonal coordinate system following the centreline of each vessel, we obtain the inertial forces (centrifugal, Coriolis, and torsional) explicitly, which directly depend on vascular curvature and torsion. We then analyse the individual roles of the inertial, pressure gradient, and viscous forces on the patterns of primary and secondary velocities, vortical structures, and wall stresses in each cross section. We also consider cross-sectional averages of the in-plane components of these forces, which can be thought of as reducing the dynamics of secondary flows onto the vessel centreline. At Reynolds numbers between 50 and 500, secondary motions in the directions of the local normals and binormals behave as two underdamped oscillators. These oscillate around the fully developed state and are coupled by torsional forces that break the symmetry of the flow. Secondary flows are driven by the centrifugal and torsional forces, and these are counterbalanced by the in-plane pressure gradients generated by the wall reaction. The viscous force primarily opposes the pressure gradient, rather than the inertial forces. In the axial direction, and depending on the secondary motion, the curvature-dependent Coriolis force can either enhance or oppose the bulk of the axial flow, and this shapes the velocity profile. For bends with little or no torsion, the Coriolis force tends to restore flow axisymmetry. The maximum circumferential and axial wall shear stresses along the centreline correlate well with the averaged in-plane pressure gradient and the radial displacement of the peak axial velocity, respectively. We conclude with a discussion of the physiological implications of these results. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3694526]
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available