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Transition to turbulence within an eccentric stenosis geometry under steady flow using laser Doppler vibrometry for a non-Newtonian and Newtonian fluid

Rayanne, Pinto Costa
http://rave.ohiolink.edu/etdc/view?acc_num=akron1605627935635379

Abstract Details

2020, Master of Science in Engineering, University of Akron, Mechanical Engineering.
The blood flow inside the human is mostly laminar[4]. However, complex geometries (such as stenoses and arteriovenous grafts) can cause turbulence in the flow [16,6]. Stenosis is a narrowing of the artery wall, which can cause heart attacks and strokes. Many numerical and experimental studies have been trying to characterize the transition to turbulence in these complex geometries. One of the ramifications of the present research focuses on verifying if the assumption that blood can be represented as a Newtonian fluid at higher shear rates (>200 1/s) with particular emphasis on the impact of the transition to turbulence. Studies have revealed a delay, a higher Reynolds number, for blood compared to Newtonian fluid in the transition to turbulence [2,3]. These studies were conducted in a rigid wall flow model. It is unclear if the fluid-solid interaction in a flexible wall model would play an important role in the transition to turbulence. Therefore, the present study aimed to further contribute to this research topic by measuring the wall vibration in a flexible tube downstream eccentric stenosis under steady flow conditions. The Reynolds number ranged from 200 to 750. The wall vibration measurements did not show a delay in the transition to turbulence for blood compared to a Newtonian fluid. The average root mean square (RMS) wall velocity amplitude for blood was slightly smaller than that for water-glycerin (WG), which could be a result of the shear-thinning or viscoelastic properties of blood. The wall vibration measurements showed less vibration near the stenosis compared to further downstream. In conclusion, computational fluid dynamics simulations may be able to take advantage of a Newtonian assumption for whole blood with respect to the transitional nature of flow in a flexible wall artery based on the present study's results.
Francis Loth (Advisor)
Siamak Farhad (Committee Member)
Alex Povitsky (Committee Member)
125 p.
Engineering
Non-Newtonian; blood; transition to turbulence; stenosis

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Citations

  • Rayanne, P. C. (2020). Transition to turbulence within an eccentric stenosis geometry under steady flow using laser Doppler vibrometry for a non-Newtonian and Newtonian fluid [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605627935635379

    APA Style (7th edition)

  • Rayanne, Pinto Costa. Transition to turbulence within an eccentric stenosis geometry under steady flow using laser Doppler vibrometry for a non-Newtonian and Newtonian fluid. 2020. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1605627935635379.

    MLA Style (8th edition)

  • Rayanne, Pinto Costa. "Transition to turbulence within an eccentric stenosis geometry under steady flow using laser Doppler vibrometry for a non-Newtonian and Newtonian fluid." Master's thesis, University of Akron, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605627935635379

    Chicago Manual of Style (17th edition)

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