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Control of Blood Flow by Endothelial-Secreted Biochemicals NO, Ca2+ and Growth Factor VEGF: Numerical Simulation Using Lattice Boltzmann-Finite Difference Hybrid

Asghanian, Alireza | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53899 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar
  7. Abstract:
  8. Endothelial cells that cover the inner wall of blood cells and are sensitive to receiving mechanical signals play important role in regulating many vital activities of the human body especially the function of the cardiovascular system. One of the factors affecting the mechanical functions of these cells is the shear stress applied to them. Due to blood velocity increasing or decreasing the endothelial cells shear stress change and leads to some chemical reactions and finally releasing biochemical substances including Nitrogen-Monoxide and Calcium-ion. Nitrogen-Monoxide produced by endothelial cells by affecting the smooth muscle cells in the vessel wall causes dilating of the vessel wall, reduction of shear stress in the walls of arteries, reduction heart load and regulating cardiovascular system's function. In the present study the vascular vasodilation process due to shear stress on endothelial cells and Nitrogen-Monoxide's producing was simulated by numerical method Lattice-Boltzmann. For this purpose a two dimensional of coronary vessel with a porous wall is considered. By solving the intravenous flow equations (Continuity and Navier-Stokes) and its wall (Continuity and Darcy), the amount of shear stress on endothelial cells has been calculated. In the next step using a hyperbolic function (calculated based on experimental data), mentioned in chapter3 and holding the shear stress, the amount of the Nitrogen-Monoxide production by these cells was calculated. Then by calculating the concentration of Nitrogen-Monoxide and using a model that shows the dependency of vessel diameter' change, the radial shear rate was obtained 0.144, Also the half-time of Nitrogen-Monoxide was obtained 1.1s. this value indicates the time required from the beginning of production to elimination of Nitrogen-Monoxide in the vessel wall. This number is compared with the results reported in other articles and matches. other result of the present work includes the strong dependency of Nitrogen-Monoxide production on shear stress on endothelial cells which by increasing the amount of shear stress on endothelial cells. All of these steps were simulated numerically by Lattice-Boltzmann method
  9. Keywords:
  10. Endothelial Cell ; Lattice Boltzmann Method ; Wall Shear Stress (WSS) ; Nitrogen Monoxide ; Radial Shear Rate

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