Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM

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dc.contributor.advisorChinyoka, Tirivanhu
dc.contributor.authorNagarathnam, Sunitha
dc.date.accessioned2022-08-30T07:42:16Z
dc.date.available2022-08-30T07:42:16Z
dc.date.issued2022
dc.date.updated2022-08-30T06:33:05Z
dc.description.abstractNumerical simulations of the complex flows of complex (viscoelastic) fluids are investigated. The primary fluid investigated in this thesis is human blood, a complex fluid which can be modelled via viscoelastic constitutive models. The most commonly used constitutive models for viscoelastic fluids include the OldroydB, Giesekus, Johnson-Segalman, Finitely Extensible Non-Linear Elastic (FENE), Phan-Thein-Tanner (PTT) models etc. Our Numerical approach is based on the finite volume methods implemented on the OpenFOAM platform. We employ the Giesekus, Oldroyd-B, and Generalized Oldroyd-B viscoelastic constitutive models in this thesis, depending on the underlying context. Numerical validation of our results is conducted via the most used benchmark flow problems for viscoelastic fluid flow. The robust and efficient numerical methodologies are then deployed to investigate the flow characteristics, and hence illustrate various novel behavior, for blood flow in stenosed and bifurcated arteries. The present work took advantage of the availability of a reasonable set of viscoelastic constitutive model solvers within OpenFOAM, specifically the viscoelasticFluidFoam solver which we modified and developed to suit our focused needs for blood flow computations. The modified computational algorithms were successfully validated against well-known benchmark flow problems in the literature. Noting that the Giesekus viscoelastic constitutive model is a generalization of both the Oldroyd-B and Generalized Oldroyd-B models, the validation of results is carried out via the Giesekus model enabling us to develop a general-purpose code capable of simulating several viscoelastic constitutive models. The main results were otherwise presented for the Oldroyd-B and Generalized Oldroyd-B models as these are the most applicable to blood flow modelling. The results demonstrate that the velocity spurt through the stenosis is directly proportional to the constriction caused by the stenosis. The higher the blockage from the constriction, the higher the corresponding velocity spurt through the constriction. This velocity behavior, as the constriction blockage increases, correspondingly increase the wall shear stresses. High wall shear stresses significantly increase the possibility of rupture of the stenosis/blockage. This can lead to catastrophic consequences in the usual case where the stenosis is caused by tumor growth.
dc.identifier.apacitationNagarathnam, S. (2022). <i>Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM</i>. (). ,Faculty of Science ,Department of Mathematics and Applied Mathematics. Retrieved from http://hdl.handle.net/11427/36743en_ZA
dc.identifier.chicagocitationNagarathnam, Sunitha. <i>"Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM."</i> ., ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2022. http://hdl.handle.net/11427/36743en_ZA
dc.identifier.citationNagarathnam, S. 2022. Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM. . ,Faculty of Science ,Department of Mathematics and Applied Mathematics. http://hdl.handle.net/11427/36743en_ZA
dc.identifier.ris TY - Doctoral Thesis AU - Nagarathnam, Sunitha AB - Numerical simulations of the complex flows of complex (viscoelastic) fluids are investigated. The primary fluid investigated in this thesis is human blood, a complex fluid which can be modelled via viscoelastic constitutive models. The most commonly used constitutive models for viscoelastic fluids include the OldroydB, Giesekus, Johnson-Segalman, Finitely Extensible Non-Linear Elastic (FENE), Phan-Thein-Tanner (PTT) models etc. Our Numerical approach is based on the finite volume methods implemented on the OpenFOAM platform. We employ the Giesekus, Oldroyd-B, and Generalized Oldroyd-B viscoelastic constitutive models in this thesis, depending on the underlying context. Numerical validation of our results is conducted via the most used benchmark flow problems for viscoelastic fluid flow. The robust and efficient numerical methodologies are then deployed to investigate the flow characteristics, and hence illustrate various novel behavior, for blood flow in stenosed and bifurcated arteries. The present work took advantage of the availability of a reasonable set of viscoelastic constitutive model solvers within OpenFOAM, specifically the viscoelasticFluidFoam solver which we modified and developed to suit our focused needs for blood flow computations. The modified computational algorithms were successfully validated against well-known benchmark flow problems in the literature. Noting that the Giesekus viscoelastic constitutive model is a generalization of both the Oldroyd-B and Generalized Oldroyd-B models, the validation of results is carried out via the Giesekus model enabling us to develop a general-purpose code capable of simulating several viscoelastic constitutive models. The main results were otherwise presented for the Oldroyd-B and Generalized Oldroyd-B models as these are the most applicable to blood flow modelling. The results demonstrate that the velocity spurt through the stenosis is directly proportional to the constriction caused by the stenosis. The higher the blockage from the constriction, the higher the corresponding velocity spurt through the constriction. This velocity behavior, as the constriction blockage increases, correspondingly increase the wall shear stresses. High wall shear stresses significantly increase the possibility of rupture of the stenosis/blockage. This can lead to catastrophic consequences in the usual case where the stenosis is caused by tumor growth. DA - 2022_ DB - OpenUCT DP - University of Cape Town KW - Blood flow KW - Stenosed and bifurcating artery KW - Viscoelastic fluid KW - Oldroyd-B model KW - Generalized Oldroyd-B model KW - Giesekus Model KW - Numerical Simulation KW - Finite volume methods KW - OpenFOAM LK - https://open.uct.ac.za PY - 2022 T1 - Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM TI - Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM UR - http://hdl.handle.net/11427/36743 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/36743
dc.identifier.vancouvercitationNagarathnam S. Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM. []. ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2022 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/36743en_ZA
dc.language.rfc3066eng
dc.publisher.departmentDepartment of Mathematics and Applied Mathematics
dc.publisher.facultyFaculty of Science
dc.subjectBlood flow
dc.subjectStenosed and bifurcating artery
dc.subjectViscoelastic fluid
dc.subjectOldroyd-B model
dc.subjectGeneralized Oldroyd-B model
dc.subjectGiesekus Model
dc.subjectNumerical Simulation
dc.subjectFinite volume methods
dc.subjectOpenFOAM
dc.titleSimulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationlevelPhD
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