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Numerical assessment of pulsatile flow through diverging tees with a sharp- and round-edge junction

Numerical assessment of pulsatile flow through diverging tees with a sharp- and round-edge junction
Numerical assessment of pulsatile flow through diverging tees with a sharp- and round-edge junction

Unsteady flow through diverging tees is of interest in many industrial systems and physiological applications. In this study, the characteristics of the transient flow behaviors at the junctions of diverging tees with sharp- and round-edge junctions were investigated numerically based on physiological boundary conditions. The flow conditions were characterized based on a Newtonian fluid analogous to blood with a Womersley number of 23.13 and a mean inlet Reynolds number of 652. The results from this study demonstrate the onset conditions of flow separation at the upstream end of both branches and the relationship between the axial and secondary flow fields. For both junctions, the onset condition of separation and the strength of recirculation correspond closely to the momentum of the secondary boundary layer adjacent to the inner-wall of the branch. The nature of the boundary layer is strongly dependent on the structures of the vortical cells. The round-edge junction attenuates the strength of recirculation by triggering flow separation at a much lower flow rate ratio. The strength of the recirculation was found to be inversely proportional to the strength of the secondary flow. The reduction of the strength of recirculation leads to an increase in wall shear stress level and a decrease in oscillation effects.

Bypass graft, Flow separation, Hemodynamic shear stress, Pulsating flows, Recirculating vortices, Secondary flow, T-junction
0142-727X
1-13
Kok, Foo
9c965216-c916-493c-9d7d-b58e72ced83a
Myose, Roy
a9430613-211a-42bf-8fe8-42d8a9cf8859
Hoffmann, Klaus A.
2e1a3d05-6c4f-476d-bd57-4d2cfd41f5f5
Kok, Foo
9c965216-c916-493c-9d7d-b58e72ced83a
Myose, Roy
a9430613-211a-42bf-8fe8-42d8a9cf8859
Hoffmann, Klaus A.
2e1a3d05-6c4f-476d-bd57-4d2cfd41f5f5

Kok, Foo, Myose, Roy and Hoffmann, Klaus A. (2019) Numerical assessment of pulsatile flow through diverging tees with a sharp- and round-edge junction. International Journal of Heat and Fluid Flow, 76, 1-13. (doi:10.1016/j.ijheatfluidflow.2019.01.008).

Record type: Article

Abstract

Unsteady flow through diverging tees is of interest in many industrial systems and physiological applications. In this study, the characteristics of the transient flow behaviors at the junctions of diverging tees with sharp- and round-edge junctions were investigated numerically based on physiological boundary conditions. The flow conditions were characterized based on a Newtonian fluid analogous to blood with a Womersley number of 23.13 and a mean inlet Reynolds number of 652. The results from this study demonstrate the onset conditions of flow separation at the upstream end of both branches and the relationship between the axial and secondary flow fields. For both junctions, the onset condition of separation and the strength of recirculation correspond closely to the momentum of the secondary boundary layer adjacent to the inner-wall of the branch. The nature of the boundary layer is strongly dependent on the structures of the vortical cells. The round-edge junction attenuates the strength of recirculation by triggering flow separation at a much lower flow rate ratio. The strength of the recirculation was found to be inversely proportional to the strength of the secondary flow. The reduction of the strength of recirculation leads to an increase in wall shear stress level and a decrease in oscillation effects.

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More information

Accepted/In Press date: 9 January 2019
e-pub ahead of print date: 22 January 2019
Published date: 1 April 2019
Keywords: Bypass graft, Flow separation, Hemodynamic shear stress, Pulsating flows, Recirculating vortices, Secondary flow, T-junction

Identifiers

Local EPrints ID: 433926
URI: http://eprints.soton.ac.uk/id/eprint/433926
ISSN: 0142-727X
PURE UUID: 793997d5-6d19-47e7-b6e0-9cb37f7065ef

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Date deposited: 06 Sep 2019 16:30
Last modified: 16 Mar 2024 03:31

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Contributors

Author: Foo Kok
Author: Roy Myose
Author: Klaus A. Hoffmann

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