Mixing through stirring of steady flow in small amplitude helical tubes. Export

@article{citeulike:3913630, abstract = {In this paper we numerically simulate flow in a helical tube for physiological conditions using a co-ordinate mapping of the Navier-Stokes equations. Helical geometries have been proposed for use as bypass grafts, arterial stents and as an idealized model for the out-of-plane curvature of arteries. Small amplitude helical tubes are also currently being investigated for possible application as A-V shunts, where preliminary in vivo tests suggest a possibly lower risk of thrombotic occlusion. In-plane mixing induced by the geometry is hypothesized to be an important mechanism. In this work, we focus mainly on a Reynolds number of 250 and investigate both the flow structure and the in-plane mixing in helical geometries with fixed pitch of 6 tube diameters (D), and centerline helical radius ranging from 0.1 D to 0.5 D. High-order particle tracking, and an information entropy measure is used to analyze the in-plane mixing. A combination of translational and rotational reference frames are shown to explain the apparent discrepancy between flow field and particle trajectories, whereby particle paths display a pattern characteristic of a double vortex, though the flow field reveals only a single dominant vortex. A radius of 0.25 D is found to provide the best trade-off between mixing and pressure loss, with little increase in mixing above R=0.25 D, whereas pressure continues to increase linearly.}, author = {Cookson, A. N. and Doorly, D. J. and Sherwin, S. J.}, citeulike-article-id = {3913630}, citeulike-linkout-0 = {http://dx.doi.org/10.1007/s10439-009-9636-y}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/19148753}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=19148753}, citeulike-linkout-3 = {http://www.springerlink.com/content/r340x66078g7v108}, doi = {10.1007/s10439-009-9636-y}, issn = {1521-6047}, journal = {Annals of biomedical engineering}, keywords = {device, flow, helical, numerical, secondaryflow}, month = {April}, number = {4}, pages = {710--721}, posted-at = {2009-11-13 13:30:12}, priority = {2}, title = {Mixing through stirring of steady flow in small amplitude helical tubes.}, url = {http://dx.doi.org/10.1007/s10439-009-9636-y}, volume = {37}, year = {2009} }

TY - JOUR ID - citeulike:3913630 L3 - citeulike-article-id:3913630 N2 - In this paper we numerically simulate flow in a helical tube for physiological conditions using a co-ordinate mapping of the Navier-Stokes equations. Helical geometries have been proposed for use as bypass grafts, arterial stents and as an idealized model for the out-of-plane curvature of arteries. Small amplitude helical tubes are also currently being investigated for possible application as A-V shunts, where preliminary in vivo tests suggest a possibly lower risk of thrombotic occlusion. In-plane mixing induced by the geometry is hypothesized to be an important mechanism. In this work, we focus mainly on a Reynolds number of 250 and investigate both the flow structure and the in-plane mixing in helical geometries with fixed pitch of 6 tube diameters (D), and centerline helical radius ranging from 0.1 D to 0.5 D. High-order particle tracking, and an information entropy measure is used to analyze the in-plane mixing. A combination of translational and rotational reference frames are shown to explain the apparent discrepancy between flow field and particle trajectories, whereby particle paths display a pattern characteristic of a double vortex, though the flow field reveals only a single dominant vortex. A radius of 0.25 D is found to provide the best trade-off between mixing and pressure loss, with little increase in mixing above R=0.25 D, whereas pressure continues to increase linearly. IS - 4 JF - Annals of biomedical engineering SN - 1521-6047 EP - 721 TI - Mixing through stirring of steady flow in small amplitude helical tubes. VL - 37 SP - 710 KW - device KW - flow KW - helical KW - numerical KW - secondaryflow AU - Cookson, AN AU - Doorly, DJ AU - Sherwin, SJ PY - 2009/04// UR - http://dx.doi.org/10.1007/s10439-009-9636-y ER -