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1.
鼻腔结构的三维重建与气体流场数值模拟   总被引:4,自引:0,他引:4  
根据某鼻腔疾病患者的CT图像,用表面重建的方法对该患者的鼻腔结构进行三维重建,根据统计得出的呼吸潮气量以及呼吸周期假设一个呼吸周期内的鼻腔中气流流速的变化。用有限元的方法对鼻腔域中的气体流动进行了数值模拟及分析,并把得到的结果与医学文献中记载的数据相比较,说明本文计算结果是可信的。从文中的数值结果可以定量得到人体呼吸过程中,气体流场在鼻腔中的分布。  相似文献   

2.
鼻腔气道结构对鼻腔加温加湿功能影响的数值模拟   总被引:1,自引:0,他引:1  
目的研究鼻腔气道结构的变化对鼻腔加温加湿功能的影响。方法选取9例正常人和2例鼻中隔偏曲患者(术前术后)作为研究对象,建立鼻腔的三维有限元模型,数值模拟鼻腔气道中的气流分布、气流温度和湿度,并对比正常人与病患、术前与术后的数值模拟结果。结果鼻腔气道宽敞一侧气流体积流率相对较大,加温加湿效果差;狭窄一侧加温效果相对较好。对于正常人,鼻腔对吸入气流加温加湿的部位主要位于前端;对于病患,则要取决于鼻腔的气道结构。结论鼻腔气道结构影响鼻腔对吸入气流的加温加湿效果,鼻腔气道结构的几何参数如鼻腔气道壁面积、鼻腔体积可以用来衡量鼻腔对气流的加温加湿效果。  相似文献   

3.
目的建立上气道、气管及部分支气管的生物力学模型,研究不同呼吸模式对气道内气流特性以及气道阻力的影响。方法根据CT扫描资料,建立包括鼻腔、口腔、咽、喉、气管和部分支气管在内的具有真实解剖结构形态的三维有限元呼吸道模型,针对现实中几种典型情况,数值模拟流经鼻、口的气流不同比例情况下气道内的气流特性。结果当仅有少量气流经由口腔吸入时,呼吸道内气流的分布规律以及各部位气道阻力的大小与完全经由鼻腔呼吸的情况相似。当口腔吸入或呼出大量气体,气流主要经由口腔与外界进行交换时,呼吸道内气流场、压力场和剪应力场分布规律明显不同,主要区别体现在鼻腔、口腔气道内。结论建立上气道与气管、支气管生物力学模型,可以从整体上了解呼吸过程中整个上气道至部分支气管中气流的分布情况,为了解与上气道结构相关疾病的发病机制建立数值研究平台。  相似文献   

4.
鼻腔结构矫正手术对OSAHS患者上气道流场影响的数值分析   总被引:1,自引:0,他引:1  
目的研究伴鼻腔结构异常的OSAHS患者经鼻腔结构矫正手术后,气道结构形态的改变对患者整个上气道流场分布以及软腭运动姿态的影响。方法基于患者手术前后CT影像学数据,建立上气道及软腭三维有限元模型,采用流固耦合的方法模拟手术前后上气道流场特性及软腭的运动情况。结果手术矫正了异常的鼻腔结构形态,鼻腔及整个上气道阻力明显下降。术后软腭的肥厚水肿明显缓解,其游离缘的运动幅度减小。软腭运动幅度随弹性模量的减小而增大。术后的模拟结果与文献报道的正常人实验与模拟结果接近。结论鼻腔结构矫正手术改变了上气道结构,影响了气流流场的分布和软腭的运动姿态;不同病理生理状态下,软腭弹性模量的变化对其运动姿态有影响。  相似文献   

5.
一氧化氮(nitric oxide,NO)在鼻腔内参与抗菌、抗病毒、促进鼻黏膜纤毛摆动、调节鼻黏膜血管扩张等多种生理功能。 NO 浓度异常会导致多种鼻腔疾病的发生,已成为临床常规检测气道炎症的生物学指标。 随着医学与力学等领域的深入交叉,运用数值研究方法,与传统的实验方法相结合,对鼻腔内 NO 浓度分布进行分析,可量化鼻腔内各处 NO 浓度,获得鼻腔内 NO 的分布规律,辅助相关鼻腔疾病的临床诊疗,有助于推动精准医疗的发展。 本文对鼻腔内 NO 浓度分布实验研究及数值研究的进展进行综述,并对未来研究方向进行展望。  相似文献   

6.
鼻不仅是气体出入的腔道,同时也是嗅觉感受器.它可分为外鼻、鼻腔和鼻旁窦3部分.鼻腔可分为鼻前庭和固有鼻腔2部分.固有鼻腔为鼻腔的主要部分,根据鼻黏膜的结构和功能特点分为2区:呼吸区和嗅区.呼吸区为上鼻甲对应平面以下的部分,范围较广,黏膜颜色呈红色或粉红色,并与鼻旁窦黏膜延续.嗅区为上鼻甲平面以上包括鼻中隔相应的部分[1-2],黏膜呈浅黄色或苍白色,其内含有嗅细胞,感受嗅觉刺激[3].但是在传统教科书和一些相关著作中关于鼻中隔的嗅区黏膜边界从未做出详细叙述,为此进行了相关的观察研究.  相似文献   

7.
目的:建立一个基于健康人体的、系统的、具有高度几何相似性的足部三维有限元模型,并用此模型静态地分析人体双足站立相时的足部内部的生物力学特性,量化足部内部的应力/应变状况、足部内侧纵弓变化等。方法:基于志愿者右足的3维CT层切数据,对足踝系统相关组织进行几何重建及其网格划分,建立完整的有限元模型并对人体站立状态进行了静态模拟。结果:站立姿态下的足底表面接触压力分布、内部软组织应力分布以及内侧足弓的变形等人体足部生物力学特性被量化。结论:本研究中创建的三维有限元足部模型,经验证是一个正确、可靠的模型,可以帮助临床医生和其他研究人员更好的理解足部内部的许多生物力学特性。  相似文献   

8.
目的求解支架扩张过程中的应力、形变分布云图,以及压强-直径变化曲线,获取球囊扩张式支架整体性能数据。方法使用"体积控制"球囊-支架模型,运用有限元分析软件ANYSY进行数值模拟,并与实验数据进行比较。结果支架-球囊模型可以很好地模拟支架扩张全过程;当球囊膨胀至最大直径,支架模型的主体结构与加强筋连接位置会发生塑性形变,而最大应力也分布在连接位置。结论通过有限元分析可以对支架性能进行优化。  相似文献   

9.
背景:以实验动物模拟人类相关疾病是研究疾病发生发生及治疗的基础,鼻腔、鼻窦疾病也需要恰当实验动物作为其模型。目的:观察兔鼻腔、鼻窦的CT和局部解剖表现,探讨兔应用于鼻窦炎动物模型的可行性。方法:利用CT使用常规鼻窦冠状位与水平位扫描新西兰兔,随后进行常规鼻腔、鼻窦解剖学观察。结果与结论:兔鼻中隔将鼻腔分为左右两个腔,鼻腔外侧壁由上颌鼻甲、中间鼻甲、内侧鼻甲、下鼻甲组成,上颌窦窦腔最大,筛窦、蝶窦、额窦相对较小,以上结构均对称分布。兔鼻腔、鼻窦在CT扫描下显示清晰。兔鼻腔、鼻窦的解剖与人类鼻腔、鼻窦解剖结构既有相似也有不同,其上颌窦解剖部位与人相似且窦腔较大便于操作,具有动物实验模型建立的可行性,适用于鼻窦炎动物模型建立,可应用于模拟人类鼻窦炎的研究。  相似文献   

10.
目的建立物理模型实验和数值模拟相结合的方法,用于研究上呼吸道气流状态。方法基于网上公开CT医学图像,重建人体上呼吸道三维模型。基于3D打印技术,建立上呼吸道实验模型,进行呼吸的流量过程测量实验;通过对上呼吸道三维模型进行网格划分,采用湍流Realizable k-ε数值模型进行计算。结果首先进行与实验工况对应的数值模拟对比研究,得到与实验吻合的结果。数值模拟结果表明,呼吸过程中的气流的流动轨迹呈抛物线形状,呼气和吸气阶段的流场、壁面压力和涡结构分布很大区别,呼吸交换过程中上下鼻道有空气残留。另外,通过脉线、压力分布和涡结构分布情况,初步分析气流对上呼吸道生理环境的影响。结论该方法具有针对性、快速性和准确性的特点,充分发挥了物理实验可靠和数值模拟精细的优点,适用于不同个案上呼吸道不同问题的研究,对临床个性化诊疗具有价值。  相似文献   

11.
Knowledge of airflow characteristics in the nasal cavity is essential to understanding the physiologic and pathologic aspects of nasal breathing. Airflows inside post-surgery models were investigated both experimentally and numerically to simulate the inferior turbinectomy. The left cavities of all three models are normal and right cavity is modified by (1) excision of the head of the inferior turbinate, (2) resection of the lower fifth of the inferior turbinate, and (3) resection of almost the entire inferior turbinate. Thin-slice CT (computed tomography) data (0.6mm deep) and meticulous refinement of the model surface by over a decade-long collaboration between engineers and an experienced ENT doctor resulted in the creation of sophisticated nasal cavity models. After numerical experiments and validation by comparison with the PIV results, the CFD code using the Reynolds stress turbulent model and variable temperature boundary condition on the mucosal wall was chosen as the proper numerical framework. Both global quantities (pressure drop, flow rate ratio, total wall heat transfer) and local changes (velocity, temperature, humidity, pressure gradient, and wall shear stress) were numerically investigated. The turbinectomy obviously altered the main stream direction. The flow rate in the upper airway near the olfactory slit decreased in models (1) and (3). This may weaken the olfactory function of the nose. Fluid and thermal properties that are believed to be related with physiology and prognosis are dependent on turbinate resection volume, position, and manner. Widening of the inferior airway does not always result in decreased flow resistance or wall heat transfer. The gains and losses of inferior turbinectomy were considered by analysis of the post-surgery model results. Nasal resistance was increased in model (1) due to sudden airway expansion. Nasal resistance increased and the wall heat transfer decreased in model (3) due to sudden airway expansion and excessive reduction of the mucosal wall surface area. Local shear stress and pressure gradient levels were increased in models (1) and (3).  相似文献   

12.
Airflow dynamics are recognized as being important to the functioning of the human nose in conditioning and filtering inspired air, yet these dynamics are poorly understood. Despite considerable research on airflow dynamics by otolaryngologists, respiratory physiologists, and toxicologists, major disagreements remain about the nature of airflow in the human nose. Specifically, there is little consensus about the character of nasal airflow regimes (laminar or turbulent) and about the major pathways of airflow through the internal chamber. Additionally, a number of features in the human nose have been argued to enhance airflow turbulence, thus increasing the exposure of moving air to the nasal mucosa and facilitating heat and moisture exchange in cold and/or dry climates. These features include: an inferior orientation of the nares; a nasal sill that is high relative to the floor of the internal nasal chamber; a nasal valve that is small in cross-sectional area relative to that of the internal chamber; and large, projecting conchae. The claim that these features affect airflow dynamics has never been tested. To clarify the nature of human nasal airflow and to test these claims of functional significance to nasal variation, we studied airflow across physiological flow rates using water and dye flowing through anatomically accurate acrylic models of human nasal air passageways (with adjustment of water flow rates to maintain dynamic similarity). The models were derived from direct casting of the nasal passageways of 10 Caucasian ("leptorrhine") cadavers (six male, four female). Measures of naris angle, nasal sill height, nasal valve area relative to internal chamber cross-sectional area, and relative projection of the inferior and middle turbinates were taken directly on the resulting casts. The relationships between aspects of nasal morphology and turbulent air flow were evaluated by examining the flow regimes (laminar, semiturbulent, or turbulent) at varying flow rates, with the expectation that the greater the development of the proposed turbulence-enhancing features the slower the flow rate at which flow would shift from one regime to another. Flow characteristics (both flow regimes and principal pathways) were highly variable within our sample. The relative projection of the inferior turbinate was the only variable that significantly affected the flow rate at which flow became turbulent. However, more projecting turbinates appear to laminate flow rather than to induce turbulence. Nostril orientation was moderately correlated with flow dynamics (with more inferiorly directed nares producing turbulence at slower flow rates), but this correlation was not statistically significant. Relative nasal valve area and nasal sill height were unrelated to turbulence in our models.  相似文献   

13.
In this study we utilized computational fluid dynamic (CFD) techniques to construct a numerical simulation of nasal cavity airflow pre and post virtual functional endoscopic surgery (FESS). A healthy subject was selected, and CFD techniques were then applied to construct an anatomically and proportionally accurate three-dimensional nasal model based on nasal CT scans. A virtual FESS intervention was performed numerically on the normal nasal model using Fluent software. Navier-Stokes and continuity equations were used to calculate and compare airflow, velocity, distribution and pressure in both the pre and post FESS models. In the post-FESS model, there was an increase in airflow distribution in the maxillary, ethmoid and sphenoid sinuses, and a 13% increase through the area connecting the middle meatus and the surgically opened ethmoid. There was a gradual decrease in nasal resistance in the posterior ethmoid sinus region following FESS. These findings highlight the potential of this technique as a powerful preoperative assessment tool to aid clinical decision-making.  相似文献   

14.
The nasal cavity is the main passage for air flow between the ambient atmosphere and the lungs. A preliminary requisite for any investigation of the mechanisms of each of its main physiological functions, such as filtration, air-conditioning and olfaction, is a basic knowledge of the air-flow pattern in this cavity. However, its complex three-dimensional structure and inaccessibility has traditionally prevented a detailed examination of internalin vivo orin vitro airflow patterns. To gain more insight into the flow pattern in inaccessible regions of the nasal cavity we have conducted a mathematical simulation of asymmetric airflow patterns through the nose. Development of a nose-like model, which resembles the complex structure of the nasal cavity, has allowed for a detailed analysis of various boundary conditions and structural parameters. The coronal and sagittal cross-sections of the cavity were modeled as trapezoids. The inferior and middle turbinates were represented by curved plates that emerge from the lateral walls. The airflow was considered to be incompressible, steady and laminar. Numerical computations show that the main air flux is along the cavity floor, while the turbinate structures direct the flow in an anterior-posterior direction. The presence of the turbinates and the trapezoidal shape of the cavity force more air flux towards the olfactory organs at the top of the cavity.  相似文献   

15.
16.
目的 探讨中鼻甲连续冠状位断面解剖特点,结合薄层CT扫描及3D数字重建,为自后向前的鼻窦手术提供结构解剖学基础。方法 4具(8侧)成人尸头标本,行鼻窦螺旋CT扫描获取图像后,行连续冠状位断面解剖,并对相应层面的CT图像进行结构标注,观察中鼻甲3部分的形态学特点及与CT影像的对应关系;通过薄层鼻窦CT进行3D立体数字重建中鼻甲。结果 连续冠状位断面解剖自后向前观察中鼻甲各部分形态特点为,中鼻甲水平部内侧游离端为球状并以板状结构附着于鼻腔外侧壁;板状结构向前分为前后骨板,前为筛泡基板,后为中鼻甲基板,斜行向前向上附着于脑板;在筛泡基板与中鼻甲基板之间为前组筛窦;中鼻甲垂直部自中鼻甲水平部以矢状位向上呈扇形附着于额鼻嵴及脑板;以冠状位断面解剖中鼻甲3部分典型形态标注鼻窦CT图像;完成了中鼻甲形态数字三维重建。结论 从冠状位断面形态观察,可以归纳出自后至前中鼻甲形态变化规律,为自后向前的手术径路提供解剖学依据。  相似文献   

17.
The mechanics of airflow in the human nasal airways is reviewed, drawing on the findings of experimental and computational model studies. Modelling inevitably requires simplifications and assumptions, particularly given the complexity of the nasal airways. The processes entailed in modelling the nasal airways (from defining the model, to its production and, finally, validating the results) is critically examined, both for physical models and for computational simulations. Uncertainty still surrounds the appropriateness of the various assumptions made in modelling, particularly with regard to the nature of flow. New results are presented in which high-speed particle image velocimetry (PIV) and direct numerical simulation are applied to investigate the development of flow instability in the nasal cavity. These illustrate some of the improved capabilities afforded by technological developments for future model studies. The need for further improvements in characterising airway geometry and flow together with promising new methods are briefly discussed.  相似文献   

18.
Knowledge regarding particle deposition processes in the nasal cavity is important in aerosol therapy and inhalation toxicology applications. This paper presents a comparative study of the deposition of micron and submicron particles under different steady laminar flow rates using a Lagrangian approach. A computational model of a nasal cavity geometry was developed from CT scans and the simulation of the fluid and particle flow within the airway was performed using the commercial software GAMBIT and FLUENT. The air flow patterns in the nasal cavities and the detailed local deposition patterns of micron and submicron particles were presented and discussed. It was found that the majority of micron particles are deposited near the nasal valve region and some micron particles are deposited on the septum wall in the turbinate region. The deposition patterns of micron particles in the left cavity are different compared with that in the right one especially in the turbinate regions. In contrast, the deposition for nanoparticles shows a moderately even distribution of particles throughout the airway. Furthermore the particles releasing position obviously influences the local deposition patterns. The influence of the particle releasing position is mainly shown near the nasal valve region for micron particle deposition, while for submicron particles deposition, both the nasal valve and turbinate region are influenced. The results of the paper are valuable in aerosol therapy and inhalation toxicology.  相似文献   

19.
We evaluated, by CFD simulation, effects of accessory ostium (AO) on maxillary sinus ventilation. A three-dimensional nasal model was constructed from an adult CT scan with two left maxillary AOs (sinus I) and one right AO (sinus II), then compared to an identical control model with all AOs sealed (sinuses III and IV). Transient simulations of quiet inspiration and expiration at 15L/min, and nasal blow at 48L/min, were calculated for both models using low-Reynolds-number turbulent analysis. At low flows, ventilation rates in sinuses with AOs (I≈0.46L/min, II≈0.54L/min), were both more than a magnitude higher than sinuses without AOs (III≈0.019L/min, IV≈0.020L/min). Absence of AO almost completely prevented sinus ventilation. Increased ventilation of sinuses with AOs is complex. Under high flow conditions mimicking nose blowing, in sinuses II, III, and IV, the sinus flow rate increased. In contrast, the airflow direction through sinus I reversed between inspiration and expiration, while it remained almost constant throughout the respiration cycle in sinus II. CFD simulation demonstrated that AOs markedly increase maxillary sinus airflow rates and alter sinus air circulation patterns. Whether these airflow changes impact maxillary sinus physiology or pathophysiology is unknown.  相似文献   

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