Computational investigation of turbulent, non-Newtonian flow in heart valve conduits

Tansley, G.D., 1988. Computational investigation of turbulent, non-Newtonian flow in heart valve conduits. PhD, Nottingham Trent University.

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Abstract

Heart valve conduit prosthesis design has, to date, simply incorporated an existing aortic or mitral valve prosthesis into a length of cylindrical graft tubing. However, as these valves are developed to control flow between the large chambers of the heart, their use in conduits ignores the potential benefits that might be afforded by a "purpose-built" conduit valve.

The purpose of this thesis is to describe the design and assessment of haemodynamics of such a valve, aided via the application of computational fluid Mechanics (CFM).

First a computational model of blood flow was developed which was based on a k - ϵ model of turbulence coupled with a constitutive equation to describe the non-Newtonian flow behaviour of blood. This was applied to a ball valve conduit with a diverging/converging form, and appraisal was made of pressure drop, flow fields, occluder stability and shear components. Behavioural differences between blood analogue solution and blood were limited, thereby endorsing the use of analogues for in-vitro experiments.

The valve finally developed exhibited excellent pressure/flow characteristics, in particular a pressure drop less than half that of an ideal annulus-mounted valve. Furthermore the computational technique allows it to be sized to minimise the thromboembolic and haemolytic potentials (based on predicted shear rate and shear stresses) for any individual patient, rather than simply to fit an annulus.

The major conclusions are: i) the additional flow parameter information, especially thromboembolic and haemolytic potentials, gained from applying CFM at the design stage of valve development is invaluable ii) employment of a realistic constitutive function for non-Newtonian modelling of blood flow provides the standard against which other flow models should be compared iii) greatly improved flow characteristics may be realised with purpose built valved conduits.

Item Type:	Thesis
Creators:	Tansley, G.D.
Date:	1988
ISBN:	9781369323092
Identifiers:	Number Type PQ10290060 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	16 Jun 2021 11:11
Last Modified:	21 Sep 2023 10:39
URI:	https://irep.ntu.ac.uk/id/eprint/43082

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