Browsing by Author "Yazdekhasti,A."

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Citation Count: 1
The influences of artery radii and stenosis severity on the thermal behavior of blood by employing Sisko and Lumen models: Numerical study
(Elsevier B.V., 2024) Gataa,I.S.; Salahshour, Soheıl; Salahshour,S.; Yazdekhasti,A.; AL-Hamairy,A.K.; Baghaei,S.
Artery stenosis occurs when blood vessels do not supply enough blood and oxygen due to blockage by a fatty mass called plaque. In this work, the influence of stenosis on the Nusselt number (Nu) for non-Newtonian blood flow is studied by the FVM method and using fluent software. Also, the artery is simulated based on the Lumen model. In this research, at first, it is assumed that stenosis severity increases as much as 20 %, 30 %, and 40 % of the internal cross-section area of the artery respectively while the radius is constant, then the stenosis severity is fixed at 40 %, and only radius of artery increases from 0.002 m to 0.0025, 0.0030, and 0.0035 m. The artery wall is affected by constant heat flux and Nusselt numbers in every stage as a significant parameter in each flow are calculated. It should be mentioned that the Nusselt numbers are achieved both in the direction of flow and perpendicular to one. The results show that an increase of stenosis severity from 20 % to 40 % and a decrease of the artery radius between 0.002 and 0.0035 m leads to Nusselt number enhancement due to acceleration of blood flow and increase of heat transfer while the maximum values of Nusselt number remain no change approximately. Therefore, influences of stenosis size on the thermal behavior of blood in the artery are not noticeable, and thermal risks are ignorable. © 2024 The Author(s)
Citation Count: 0
Influences of stenosis and transplantation on behavior of blood flow in the host and grafted vessels using computational fluid dynamics
(Elsevier B.V., 2024) Gataa,I.S.; Salahshour, Soheıl; Mozoun,M.A.; jumaah,M.D.; Salahshour,S.; Yazdekhasti,A.; Esmaeili,S.
In this research, the changes of wall shear stress (WSS) of flow blood affected by stenosis and grafted vessels are studied. For the simulation of non-Newtonian fluid, blood in this paper, the Carreau fluid model is used. The severity of the stenosis is considered to reduce the internal cross-sectional area of the host vessel by 30 %. In this paper, simulations are performed on the human body in sports, which are classified into anemia (LHD), normal (NHD) and high blood pressure (HHD). Results are presented in three sections including after stenosis region, transplantation section, and after transplantation region by calculating wall shear stress (WSS). It is reported that wall shear stress is increased after stenosis location due to immediate variation in the cross-section area when blood flows. To explain, Stenosis reduces the cross-section area of the vessel which causes flow contraction. Consequently, this phenomenon increases flow velocity in the central region of blood flow whereas, after passing from stenosis, blood flow is exposed to an abrupt expansion which causes flow back from the central region to wall vicinity in lateral regions of the vessel. Maximum amounts of wall shear stress are achieved at 280 Pa, 350 Pa, and 550 Pa for anemia, normal, and hypertensive individuals in order. However, the consequence of the mentioned phenomenon in hypertensive individuals is more severe than that of anemic ones. Therefore, the geometry of veins is very important in medical surgeries to prevent vessel failure, especially in stressful points of transplantation. © 2024 The Author(s)