Bypass grafts promote blood flow impaired by a partial obstruction (stenosis) of arteries by fat accumulation. This type of system's computational modeling is used to understand the flow characteristics and look for reasons and solutions for postoperative failures. The present work deals with the effects of changes in geometry in the performance of a system consisting of an idealized partially obstructed artery and a bypass graft. The constructal design method has been employed in previous works in the analysis of such system assuming steady-state flow. In the present work, blood flow is modeled as transient and pulsatile. The constructal design method is used to determine the performance indicator (dimensionless pressure drop), constraints (system volume and stenosis degrees–50% and 75%) and degrees of freedom: junction angle (30º ≤ α ≤ 70º) and diameter ratio (0.5 ≤ D₁/D ≤ 1). The response surface methodology was used to evaluate the conditions of minimum pressure drop in transient conditions. As the junction angle decreased to 30º, and the diameter ratio increased to 1, the pressure drop decreased, and there was a considerable dependence of pressure drop on the stenosis degree. The effects of the diameter ratio were more pronounced than those of the junction angle. A resistance model based on an analogy with an electronic circuit was introduced, resulting in a correlation for the pressure drop due to the bypass. This correlation confirmed that the point \(({\alpha },{\mathrm{D}}_{1}/\mathrm{D})=({30^\circ ,1})\) is a point of minimization of flow resistance. The application of the constructal design method in hemodynamics might be an excellent alternative to configuring enhanced performance and providing valuable results to the understanding of biological flows.

旁路移植物促进因脂肪堆积导致动脉部分阻塞（狭窄）而受损的血流。此类系统的计算建模用于了解流动特性并寻找术后失败的原因和解决方案。目前的工作涉及几何形状变化对由理想化部分阻塞动脉和旁路移植物组成的系统性能的影响。结构设计方法已在以前的工作中用于分析这种假定稳态流动的系统。在目前的工作中，血流被建模为瞬态和脉动。构造设计方法用于确定性能指标（无量纲压降）、约束条件（系统体积和狭窄度– 50% 和 75%）和自由度：₁ /D ≤ 1)。响应面方法用于评估瞬态条件下最小压降的条件。随着连接角减小到30°，直径比增加到1，压降减小，压降对狭窄程度有相当大的依赖性。直径比的影响比结角的影响更明显。引入了基于与电子电路类比的电阻模型，从而得出旁路压降的相关性。这种相关性证实了点\(({\alpha },{\mathrm{D}}_{1}/\mathrm{D})=({30^\circ ,1})\)是流动阻力最小化的点。构造设计方法在血液动力学中的应用可能是配置增强性能和为理解生物流动提供有价值结果的绝佳替代方案。