The influences of artery radii and stenosis severity on the thermal behavior of blood by employing Sisko and Lumen models: Numerical study

•The effects of stenosis and the radius of the artery are studied on the Nusselt number of blood flow.•Blood is non-Newtonian fluid based on Sisko formulation.•The artery is simulated based on the Lumen model.•Different radii are used for the artery with constant stenosis.•Present mechanical research applies to medical science. 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.