The numerical implementation of the complex rheology of blood, namely the viscoelastic property, in hemodynamic simulations is still a challenge. A more accurate numerical tool is essential for diagnosis, prevention and treatment of atherosclerotic disease in arteries. In particular, in small vessels or vessels with stenosis and aneurysms, the elastic effects of blood should not be neglected. Since these are regions with high velocity gradients, the storage and release of elastic energy from red blood cells and the constant changes in shear rate have a demarked impact on the flow. Although the importance of the viscoelastic property is well emphasized in the literature, only a restrict set of authors have considered this property in their hemodynamic simulations. Thus, the aim of the present work is to go further and implement several viscoelastic models for blood in user-defined-functions of ANSYS software, in order to conclude which model is the most accurate for further applications. The Generalized Oldroyd-B (GOB) model, a quasi-linear model, and two non-linear models, the Multi-mode Giesekus and Simplified Phan-Thien/ Tanner (sPTT) models, were implemented. For right coronary arteries, velocity and wall shear stress were compared, considering a purely shear-thinning model, Carreau model, and the implemented viscoelastic models. An overall reduction of the velocity in regions of higher velocity gradients was observed, considering the non-linear viscoelastic multi-mode models (Giesekus and sPTT). Moreover, the difference in peak wall shear stress values considering these multi-mode viscoelastic models is close to half the magnitude (51%) of Carreau model solutions. Despite different arteries and hemodynamic conditions, the present results are in accordance with those found in the literature. The sPTT model should be the preferential option for further applications, since Giesekus model introduces the second normal stress difference, which so far has not been reported for blood.

在血液动力学模拟中，复杂血液流变学（即粘弹性）的数值实现仍然是一个挑战。对于动脉粥样硬化疾病的诊断，预防和治疗，更准确的数字工具必不可少。特别是在小血管或有狭窄和动脉瘤的血管中，不应忽略血液的弹性作用。由于这些区域具有较高的速度梯度，因此红血球的弹性能的存储和释放以及剪切速率的恒定变化对血流有显着影响。尽管在文献中很好地强调了粘弹性性质的重要性，但只有少数作者在其血液动力学模拟中考虑了该性质。从而，本工作的目的是进一步发展并在ANSYS软件的用户定义功能中实现几种血液的粘弹性模型，以得出哪种模型最适合进一步应用的结论。实施了广义Oldroyd-B（GOB）模型，准线性模型和两个非线性模型，即多模式Giesekus模型和简化的Phan-Thien / Tanner（sPTT）模型。对于右冠状动脉，比较了纯剪切稀疏模型，Carreau模型和已实施的粘弹性模型，比较了速度和壁切应力。考虑到非线性粘弹性多模式模型（Giesekus和sPTT），观察到较高速度梯度区域的速度总体降低。此外，考虑到这些多模态粘弹性模型，峰值剪力应力值的差异接近Carreau模型解的一半（51％）。尽管动脉和血液动力学条件不同，但目前的结果与文献中发现的一致。sPTT模型应该是进一步应用的优先选择，因为Giesekus模型引入了第二法向应力差，到目前为止，尚无关于血液的报道。