主动脉夹层(AD)是一种死亡率很高的致命性心血管疾病。目前,计算机断层扫描(CT)成像是诊断和评估主动脉疾病的主要方式,提供血管结构的详细可视化。然而,CT成像在评估主动脉内血流动力学变化方面存在局限性。最近,计算流体动力学(CFD)...主动脉夹层(AD)是一种死亡率很高的致命性心血管疾病。目前,计算机断层扫描(CT)成像是诊断和评估主动脉疾病的主要方式,提供血管结构的详细可视化。然而,CT成像在评估主动脉内血流动力学变化方面存在局限性。最近,计算流体动力学(CFD)作为一种先进的无创技术出现,可以实现血管内血流动力学状况的可视化。这项技术为临床医生提供了对主动脉疾病更全面的了解,有助于改进诊断、治疗计划和预后评估。本研究中,先模拟了一例直管的血流,将出口压力与解析解比较,结果吻合良好,验证了数值模拟的准确性。然后,模拟了一例AD的血流,并定量和定性分析收缩期和舒张期AD的压力和壁剪切应力(WSS)。结果表明,AD真腔和假腔的压差可促进主动脉壁内膜破裂,形成夹层,过低的壁面剪切力可增强血流对主动脉壁的撕裂作用,促进夹层的形成,这为今后AD的研究和临床实践提供参考。Aortic dissection (AD) is a fatal cardiovascular disease with a high mortality rate. Currently, computed tomography (CT) imaging is the primary modality for diagnosing and evaluating aortic diseases, providing detailed visualization of vascular structures. However, CT imaging has limitations in assessing the hemodynamic changes within the aorta. Recently, computational fluid dynamics (CFD) has emerged as an advanced noninvasive technique that enables the visualization of hemodynamic conditions within blood vessels. This technology provides clinicians with a more comprehensive understanding of aortic disease, facilitating improved diagnosis, treatment planning, and prognosis assessment. In this study, the blood flow of a straight tube was simulated first, and the outlet pressure was compared with the analytical solution. The results were in well agreement, which verified the accuracy of the numerical simulation. Then, we simulated the blood flow of an AD and analyzed the pressure and wall shear stress (WSS) during systolic and diastolic. The results suggest that the pressure difference between the true and false cavities may trigger intimal rupture and dissection formation, and low WSS may increase aortic wall tearing and promote dissection, which provides valuable insights for future research and clinical practice of AD.展开更多
计算流体力学是研究仿生机器鱼水动力特性的重要数值模拟方法,已在仿生学及海洋学等众多领域得到广泛应用。本文利用CNKI中文数据库及Web of Science核心合集数据库分别检索到201篇中文文献和146篇英文文献,运用Cite Space软件的文献计...计算流体力学是研究仿生机器鱼水动力特性的重要数值模拟方法,已在仿生学及海洋学等众多领域得到广泛应用。本文利用CNKI中文数据库及Web of Science核心合集数据库分别检索到201篇中文文献和146篇英文文献,运用Cite Space软件的文献计量学分析方法,对文献类型、期刊分布、发文量趋势、作者、研究机构和高被引文献进行了系统分析,并结合关键词网络知识图谱、关键词聚类图谱,探讨了计算流体力学在仿生机器鱼领域中的应用研究热点。结果表明:仿生机器鱼领域中外文献发文量呈现逐年上升趋势,且仿生类期刊及文献具有较高的影响因子与被引频次;研究学科领域涉及工程学、机器人学、力学与材料科学等多个交叉性学科;该领域内研究热点与重点方向为动力学模型、三维流场仿真、设计与制作。针对现有研究的不足,建议未来研究应深入探讨水生生物集群运动仿真、鱼类侧线感知机制和仿生机器鱼水动力试验,以期促进多学科融合,为仿生机器鱼的发展提供科学参考。展开更多
随着城市化的加快,城市人口的增多,城市内部产生人为热过量释放、空气污染、城市热岛效应等环境问题,城市空间风热环境逐渐恶化。因此,以流体力学为理论基础学科发展起来的城市空间风热环境的研究逐步增多。大量城市空间风热环境的研究...随着城市化的加快,城市人口的增多,城市内部产生人为热过量释放、空气污染、城市热岛效应等环境问题,城市空间风热环境逐渐恶化。因此,以流体力学为理论基础学科发展起来的城市空间风热环境的研究逐步增多。大量城市空间风热环境的研究都以流体力学为研究理论基础,因此,本文意在梳理流体力学在城市空间风热环境研究领域的应用过程与方式。首先,本文对城市空间风热环境研究中运用流体力学的原因进行简要分析。其次,本文对空气无穷小流体元在拉格朗日坐标系下x轴方向的受力进行了深入分析,从无穷小流体元与周围流体的速度关系出发,说明其受每个力的具体原因,y、z两个方向的受力同理。之后,推导了无穷小流体元在拉格朗日坐标系下的质量守恒、动量守恒与能量守恒方程。然后,本文对城市空间风热环境研究中的边界层与空气流体的流动状态进行了简要评述,包含边界层厚度的确定方法以及湍流模型的优缺点和选取方法。最后,将青岛理工大学嘉陵江东路校区北部宿舍生活区(以下均称北区宿舍)作为城市空间风热环境的研究应用实例,运用计算流体力学软件ANSYS进行计算流体力学模拟,仿真其风热环境,得到了北区宿舍风速场、温度场与风压场。With the acceleration of urbanization and the increase of urban population, environmental issues such as excessive anthropogenic heat release, air pollution, and urban heat island effects have emerged within cities, leading to the gradual deterioration of urban wind-thermal environments. Consequently, research on urban wind-thermal environments, developed based on fluid mechanics as the theoretical foundation, has progressively increased. Since a significant body of studies on urban wind-thermal environments relies on fluid mechanics as their theoretical basis, this paper aims to systematize the application processes and methodologies of fluid mechanics in this research domain. First, this paper briefly analyzes the rationale for employing fluid mechanics in urban wind-thermal environment studies. Second, it conducts an in-depth analysis of the forces acting on an infinitesimal air fluid element along the x-axis in a Lagrangian coordinate system, explaining the specific causes of each force based on the velocity relationship between the element and its surrounding fluid. Similar analyses apply to the y- and z-axis directions. Subsequently, the mass conservation, momentum conservation, and energy conservation equations for the infinitesimal fluid element in the Lagrangian framework are derived. The paper then provides a concise review of boundary layers and airflow states in urban wind-thermal environment research, including methods for determining boundary layer thickness, as well as the advantages, limitations, and selection criteria of turbulence models. Finally, the Northern District Dormitory Area of Qingdao University of Technology’s Jialingjiang East Road Campus (hereafter referred to as the Northern Dormitory Area) is examined as a case study. Computational fluid dynamics (CFD) simulations are performed using ANSYS software to model the wind-thermal environment, yielding detailed wind speed fields, temperature fields, and wind pressure fields for the Northern Dormitory Area.展开更多
文摘主动脉夹层(AD)是一种死亡率很高的致命性心血管疾病。目前,计算机断层扫描(CT)成像是诊断和评估主动脉疾病的主要方式,提供血管结构的详细可视化。然而,CT成像在评估主动脉内血流动力学变化方面存在局限性。最近,计算流体动力学(CFD)作为一种先进的无创技术出现,可以实现血管内血流动力学状况的可视化。这项技术为临床医生提供了对主动脉疾病更全面的了解,有助于改进诊断、治疗计划和预后评估。本研究中,先模拟了一例直管的血流,将出口压力与解析解比较,结果吻合良好,验证了数值模拟的准确性。然后,模拟了一例AD的血流,并定量和定性分析收缩期和舒张期AD的压力和壁剪切应力(WSS)。结果表明,AD真腔和假腔的压差可促进主动脉壁内膜破裂,形成夹层,过低的壁面剪切力可增强血流对主动脉壁的撕裂作用,促进夹层的形成,这为今后AD的研究和临床实践提供参考。Aortic dissection (AD) is a fatal cardiovascular disease with a high mortality rate. Currently, computed tomography (CT) imaging is the primary modality for diagnosing and evaluating aortic diseases, providing detailed visualization of vascular structures. However, CT imaging has limitations in assessing the hemodynamic changes within the aorta. Recently, computational fluid dynamics (CFD) has emerged as an advanced noninvasive technique that enables the visualization of hemodynamic conditions within blood vessels. This technology provides clinicians with a more comprehensive understanding of aortic disease, facilitating improved diagnosis, treatment planning, and prognosis assessment. In this study, the blood flow of a straight tube was simulated first, and the outlet pressure was compared with the analytical solution. The results were in well agreement, which verified the accuracy of the numerical simulation. Then, we simulated the blood flow of an AD and analyzed the pressure and wall shear stress (WSS) during systolic and diastolic. The results suggest that the pressure difference between the true and false cavities may trigger intimal rupture and dissection formation, and low WSS may increase aortic wall tearing and promote dissection, which provides valuable insights for future research and clinical practice of AD.
文摘计算流体力学是研究仿生机器鱼水动力特性的重要数值模拟方法,已在仿生学及海洋学等众多领域得到广泛应用。本文利用CNKI中文数据库及Web of Science核心合集数据库分别检索到201篇中文文献和146篇英文文献,运用Cite Space软件的文献计量学分析方法,对文献类型、期刊分布、发文量趋势、作者、研究机构和高被引文献进行了系统分析,并结合关键词网络知识图谱、关键词聚类图谱,探讨了计算流体力学在仿生机器鱼领域中的应用研究热点。结果表明:仿生机器鱼领域中外文献发文量呈现逐年上升趋势,且仿生类期刊及文献具有较高的影响因子与被引频次;研究学科领域涉及工程学、机器人学、力学与材料科学等多个交叉性学科;该领域内研究热点与重点方向为动力学模型、三维流场仿真、设计与制作。针对现有研究的不足,建议未来研究应深入探讨水生生物集群运动仿真、鱼类侧线感知机制和仿生机器鱼水动力试验,以期促进多学科融合,为仿生机器鱼的发展提供科学参考。
文摘随着城市化的加快,城市人口的增多,城市内部产生人为热过量释放、空气污染、城市热岛效应等环境问题,城市空间风热环境逐渐恶化。因此,以流体力学为理论基础学科发展起来的城市空间风热环境的研究逐步增多。大量城市空间风热环境的研究都以流体力学为研究理论基础,因此,本文意在梳理流体力学在城市空间风热环境研究领域的应用过程与方式。首先,本文对城市空间风热环境研究中运用流体力学的原因进行简要分析。其次,本文对空气无穷小流体元在拉格朗日坐标系下x轴方向的受力进行了深入分析,从无穷小流体元与周围流体的速度关系出发,说明其受每个力的具体原因,y、z两个方向的受力同理。之后,推导了无穷小流体元在拉格朗日坐标系下的质量守恒、动量守恒与能量守恒方程。然后,本文对城市空间风热环境研究中的边界层与空气流体的流动状态进行了简要评述,包含边界层厚度的确定方法以及湍流模型的优缺点和选取方法。最后,将青岛理工大学嘉陵江东路校区北部宿舍生活区(以下均称北区宿舍)作为城市空间风热环境的研究应用实例,运用计算流体力学软件ANSYS进行计算流体力学模拟,仿真其风热环境,得到了北区宿舍风速场、温度场与风压场。With the acceleration of urbanization and the increase of urban population, environmental issues such as excessive anthropogenic heat release, air pollution, and urban heat island effects have emerged within cities, leading to the gradual deterioration of urban wind-thermal environments. Consequently, research on urban wind-thermal environments, developed based on fluid mechanics as the theoretical foundation, has progressively increased. Since a significant body of studies on urban wind-thermal environments relies on fluid mechanics as their theoretical basis, this paper aims to systematize the application processes and methodologies of fluid mechanics in this research domain. First, this paper briefly analyzes the rationale for employing fluid mechanics in urban wind-thermal environment studies. Second, it conducts an in-depth analysis of the forces acting on an infinitesimal air fluid element along the x-axis in a Lagrangian coordinate system, explaining the specific causes of each force based on the velocity relationship between the element and its surrounding fluid. Similar analyses apply to the y- and z-axis directions. Subsequently, the mass conservation, momentum conservation, and energy conservation equations for the infinitesimal fluid element in the Lagrangian framework are derived. The paper then provides a concise review of boundary layers and airflow states in urban wind-thermal environment research, including methods for determining boundary layer thickness, as well as the advantages, limitations, and selection criteria of turbulence models. Finally, the Northern District Dormitory Area of Qingdao University of Technology’s Jialingjiang East Road Campus (hereafter referred to as the Northern Dormitory Area) is examined as a case study. Computational fluid dynamics (CFD) simulations are performed using ANSYS software to model the wind-thermal environment, yielding detailed wind speed fields, temperature fields, and wind pressure fields for the Northern Dormitory Area.
