Computational Fluid Dynamics (CFD)
Ghanbarali Sheikhzadeh; Mahdi Mollamahdi; Mahmoud Abbaszadeh
Abstract
In this study, the momentum and energy equations of laminar flow of a non-Newtonian fluid are solved in an axisymmetric porous channel using the least square and Galerkin methods. The bottom plate is heated by an external hot gas, and a coolant fluid is injected into the channel from the upper plate. ...
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In this study, the momentum and energy equations of laminar flow of a non-Newtonian fluid are solved in an axisymmetric porous channel using the least square and Galerkin methods. The bottom plate is heated by an external hot gas, and a coolant fluid is injected into the channel from the upper plate. The arising nonlinear coupled partial differential equations are reduced to a set of coupled nonlinear ordinary differential equations using stream function.These equations can be solved using the different numerical method. The numerical solution is conducted using fourth order Rung-Kutta method. With comparing the results obtained from the analytical and numerical methods, a good adaptation can be seen between them. It can also be observed that the results of the Galerkin method have further conformity with the numerical results and the Galerkin method is simpler than the least square method and requires fewer computations. The effects of Reynolds number, Prandtl number and power law index of non-Newtonian fluid is examined on flow field and heat transfer. The results show that Nusselt number increases by increasing Reynolds number, Prandtl number, and power law index.
Biomechanics
Mehdi Jahangiri; Mohsen Saghafian; Mahmood Reza Sadeghi
Abstract
A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with non-Newtonian models using ADINA. Blood flow was considered laminar, and the arterial wall ...
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A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with non-Newtonian models using ADINA. Blood flow was considered laminar, and the arterial wall was considered rigid. Studied stenosis severities were 30, 50, and 70% of the cross-sectional area of the artery. Six non-Newtonian models were used to model the non-Newtonian behavior of blood, and their results were compared with the Newtonian model. The results showed that in Power-law and Walburn-Schneck models, unlike other models, shear stress values before and after the stenosis were smaller than Newtonian models. Also, in maximum flow rate, the Carreua, generalized Power-law, Casson, and Carreua-Yasuda models showed a reduction in global importance factor of non-Newtonian behavior, and subsequently, the results approached Newtonian model. In minimum flow rate, the global importance factor of Newtonian behavior increased, which highlighted the importance of Newtonian model. In minimum flow rate, Carreua-Yasuda model was more sensitive to the non-Newtonian behavior of blood compared to Carreua, Casson, and Power-law models. Also, in that time period, Walburn-Schneck was less sensitive to the non-Newtonian behavior of blood. On the other hand, this model did not show sensitivity when the flow rate was at its peak. Power-law model overestimated the global importance factor values. Therefore, Power-law model was not suitable, because it showed extreme sensitivity to dimension. Walburn-Schneck model was not suitable too because it lacked sensitivity.
