本文選題：氣固兩相流 + 流固耦合��； 參考：《蘇州大學(xué)》2016年碩士論文

【摘要】：當(dāng)今的世界面臨著日益嚴(yán)重的大氣污染問題,隨著汽車等工業(yè)產(chǎn)品的普及以及沙塵肆虐等災(zāi)害的頻發(fā),霧霾現(xiàn)象出現(xiàn)頻繁,呼吸道疾病的患病率大幅上升。通過研究霧霾顆粒在人體呼吸道內(nèi)運(yùn)動(dòng)和沉積的機(jī)理,對(duì)于相關(guān)的生理和病理研究具有重大的研究意義和理論價(jià)值。本文采用計(jì)算流體動(dòng)力學(xué)方法,建立了顆粒物在人體呼吸道的氣固兩相流模型,在考慮纖毛驅(qū)動(dòng)粘液運(yùn)動(dòng)的流固耦合機(jī)制的基礎(chǔ)上,建立了顆粒物在粘液纖毛系統(tǒng)中的運(yùn)動(dòng)模型,并進(jìn)行了相關(guān)的數(shù)值仿真計(jì)算。不僅從宏觀領(lǐng)域上探討了霧霾顆粒物的沉積機(jī)理,而且在微觀領(lǐng)域上對(duì)顆粒物在呼吸道壁面沉積后的運(yùn)動(dòng)規(guī)律進(jìn)行研究和探討,通過和現(xiàn)有的實(shí)驗(yàn)數(shù)據(jù)以及文獻(xiàn)的對(duì)比,證明了本文的數(shù)值計(jì)算模型以及計(jì)算方法的有效性和正確性。本文首先闡述了計(jì)算流體動(dòng)力學(xué)的基礎(chǔ)理論,對(duì)顆粒在呼吸道內(nèi)空氣流中的運(yùn)動(dòng)建立氣固兩相流模型,選用大渦模擬描述呼吸道內(nèi)氣流的運(yùn)動(dòng);分析顆粒物在空氣流中的受力情況,采用DPM模型追蹤顆粒在呼吸道內(nèi)的運(yùn)動(dòng)軌跡。然后,在人體上呼吸道物理模型基礎(chǔ)上建立剛性和彈性的呼吸道模型。研究呼吸強(qiáng)度為30L/min和90L/min時(shí),穩(wěn)態(tài)呼吸模式和循環(huán)呼吸模型下的氣流運(yùn)動(dòng)特性,計(jì)算結(jié)果表明:由于呼吸道幾何結(jié)構(gòu)的限制,氣流在聲門處會(huì)產(chǎn)生湍流噴射現(xiàn)象,在聲門上下游氣管外壁附近會(huì)發(fā)生氣流分離,產(chǎn)生回流現(xiàn)象;循環(huán)吸氣過程中,呼吸道內(nèi)的氣流軸向速度增大,在咽部和聲門下游氣管外壁處產(chǎn)生更為明顯的渦流現(xiàn)象;在呼吸道的彈性壁模型計(jì)算中,隨著呼吸道壁發(fā)生位移和變形,在口腔底部及咽喉部位,由于局部壁面出現(xiàn)凸起擴(kuò)張現(xiàn)象,其膨脹的呼吸道壁對(duì)內(nèi)部運(yùn)動(dòng)的氣流將起到“緩沖”的作用,降低氣流的速度。在此基礎(chǔ)上,分別對(duì)0.3um、2.5um和6.5um粒徑的顆粒沉積規(guī)律進(jìn)行研究,并考慮不同顆粒濃度下對(duì)顆粒沉積的影響,從而揭示了顆粒在呼吸道內(nèi)的運(yùn)動(dòng)沉積機(jī)理:顆粒粒徑的大小和人體呼吸強(qiáng)度是顆粒沉積最主要的兩個(gè)因素。不同粒徑顆粒的沉積機(jī)理不盡相同,湍流擴(kuò)散和渦流夾帶對(duì)于0.3um粒徑的顆粒是其沉積的主要因素;慣性碰撞對(duì)于6.5um粒徑的顆粒影響最大;對(duì)于2.5um粒徑的細(xì)顆粒的沉積,慣性碰撞和湍流擴(kuò)散對(duì)此粒徑的作用十分明顯。最后,選取PM2.5在支氣管內(nèi)的沉積區(qū)域的微尺度系統(tǒng)-粘液纖毛系統(tǒng)進(jìn)行研究。研究該區(qū)域纖毛擺動(dòng)規(guī)律,建立纖毛運(yùn)動(dòng)模型;分析粘液分布情況,建立具有自由液面邊界的VOF粘液流場(chǎng)模型�？紤]纖毛簇狀分布的現(xiàn)象,建立了流固耦合作用下的呼吸道粘液纖毛系統(tǒng),研究在纖毛正常擺動(dòng)情況下,上方粘液層及附著顆粒物的運(yùn)動(dòng)情況,計(jì)算結(jié)果證明了顆粒物在粘液纖毛系統(tǒng)中受到“清除”機(jī)制的作用。
[Abstract]:Nowadays, the world is facing more and more serious air pollution problems. With the popularization of industrial products such as automobiles and frequent disasters such as dust raging, the phenomenon of haze appears frequently, and the prevalence of respiratory diseases increases significantly. It is of great significance and theoretical value to study the mechanism of movement and deposition of haze particles in human respiratory tract. In this paper, a gas-solid two-phase flow model of particulate matter in human respiratory tract is established by using computational fluid dynamics (CFD). The fluid-solid coupling mechanism of ciliated mucus motion is considered. The motion model of particulate matter in mucociliary system was established and the relevant numerical simulation was carried out. Not only the deposition mechanism of haze particles is discussed from the macroscopic field, but also the motion law of particulate matter after deposition on the respiratory tract wall is studied and discussed in the micro field. The results are compared with the existing experimental data and literature. The validity and correctness of the numerical model and the calculation method are proved. In this paper, the basic theory of computational fluid dynamics (CFD) is introduced, and a gas-solid two-phase flow model is established for the movement of particles in the airflow in the respiratory tract. The large eddy simulation is used to describe the movement of the airflow in the respiratory tract. DPM model was used to track the movement of particles in the respiratory tract. Then, based on the physical model of human upper respiratory tract, a rigid and elastic model of respiratory tract is established. The characteristics of airflow movement in steady breathing mode and circulatory breathing model with respiratory intensity of 30L/min and 90L/min are studied. The results show that due to the limitation of respiratory tract geometry, turbulence jet will occur in glottis. The flow separation will occur near the outer wall of the trachea in the upper and lower reaches of the glottis, and the reflux phenomenon will occur, and the axial velocity of the airflow in the respiratory tract will increase, and the vortex phenomenon will be more obvious in the outer wall of the trachea in the pharynx and the lower part of the glottis. In the calculation of elastic wall model of respiratory tract, with the displacement and deformation of respiratory tract wall, the local wall appeared bulge and dilation phenomenon in the bottom of mouth and throat. The inflated respiratory wall acts as a buffer against the internal movement of the airflow and slows down the velocity of the airflow. On this basis, the particle deposition of 0.3um 2.5 um and 6.5um particle size was studied, and the effects of different particle concentrations on the particle deposition were considered. Therefore, the mechanism of particle movement and deposition in respiratory tract is revealed. The particle size and human respiratory intensity are the two main factors of particle deposition. The deposition mechanism of different particle size is different. Turbulent diffusion and eddy current entrainment are the main factors for the deposition of 0.3um particle, inertial collision has the greatest influence on the particle size of 6.5um, and for the deposition of fine particle size of 2.5um, the main factor is the effect of turbulence diffusion and eddy current entrainment on the deposition of 6.5um particle. The effect of inertial collision and turbulent diffusion on the particle size is very obvious. Finally, the microscale system of PM2.5 in the deposition area of bronchus, mucociliary system, was selected to study. The ciliated motion model is established and the VOF mucus flow field model with free liquid surface boundary is established by analyzing the mucus distribution. Considering the phenomenon of ciliated cluster distribution, a respiratory mucociliary system under fluid-solid coupling was established, and the motion of the upper mucous layer and attached particles was studied under the normal cilium swinging. The results show that particulate matter is "scavenging" mechanism in mucociliary system.
【學(xué)位授予單位】：蘇州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：X513

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本文編號(hào)：1985955