【摘要】：近年來(lái),隨著新興技術(shù)的出現(xiàn)和高速發(fā)展,流體動(dòng)力學(xué)面臨復(fù)雜流體和復(fù)雜流動(dòng)兩大挑戰(zhàn)。在新技術(shù)背景下,復(fù)雜流體流動(dòng)可能是多物理場(chǎng)引起的,一種物理效應(yīng)、一種化學(xué)效應(yīng)甚至一種生物效應(yīng)都可能成為驅(qū)動(dòng)流體流動(dòng)的因素,多種驅(qū)動(dòng)力及其非線性耦合使得流動(dòng)問題和與流動(dòng)伴隨的傳熱問題呈現(xiàn)復(fù)雜性、多樣性和非線性,因而需要對(duì)流動(dòng)的微觀結(jié)構(gòu)和傳輸過程進(jìn)行深入分析。作為一種拉格朗日型粒子法,能量守恒的耗散粒子動(dòng)力學(xué)方法(energy-conserving dissipative particle dynamics,e DPD)對(duì)這類具有多種驅(qū)動(dòng)力的復(fù)雜流體流動(dòng)與傳熱問題具有很大的潛力,這種新興的介觀方法應(yīng)用在傳熱領(lǐng)域不過十來(lái)年時(shí)間,而且發(fā)展相對(duì)緩慢,可謂方興未艾,還有很大的開拓空間。因而本文采用耗散粒子動(dòng)力學(xué)方法研究了多種驅(qū)動(dòng)力耦合的流動(dòng)與傳熱現(xiàn)象。首先,本文系統(tǒng)地闡述了e DPD方法應(yīng)用于流動(dòng)與傳熱現(xiàn)象模擬的理論基礎(chǔ),利用動(dòng)理論方法得到了e DPD流體系統(tǒng)所滿足的質(zhì)量守恒定律、動(dòng)量守恒定律和能量守恒定律。此外,本文詳細(xì)地闡述了耗散粒子動(dòng)力學(xué)模擬的相關(guān)細(xì)節(jié)問題,包括邊界處理、積分方法和參數(shù)選取問題,首先提出一種可行性的方案建立了耗散粒子動(dòng)力學(xué)方法中介觀參數(shù)與宏觀輸運(yùn)系數(shù)之間的聯(lián)系。根據(jù)方案,模擬了剪切力、浮升力單獨(dú)驅(qū)動(dòng)的庫(kù)艾特流動(dòng)和簡(jiǎn)單方腔內(nèi)的自然對(duì)流問題,得到的結(jié)果分別與分析解和有限體積法模擬的結(jié)果吻合很好。剪切力是工程應(yīng)用中強(qiáng)化傳熱的重要措施,因而這種剪切力與浮升力引起的混合對(duì)流問題引起了學(xué)者的極大興趣。簡(jiǎn)單方腔內(nèi)混合對(duì)流問題前人做過詳細(xì)的研究,然而工程中考慮復(fù)雜形狀很有必要。本文將耗散粒子動(dòng)力學(xué)方法應(yīng)用于內(nèi)置橢圓熱源的等溫封閉方腔內(nèi)的、剪切力與浮升力引起的、簡(jiǎn)單流體的流動(dòng)與傳熱問題。首先研究了自然對(duì)流和頂蓋驅(qū)動(dòng)流,將模擬得到的結(jié)果與其他方法如有限體積法(finite volume method,FVM)、格子玻爾茲曼方法(lattice Boltzmann method,LBM)、微分求積法(differential quadrature method,DQM)等方法進(jìn)行了比較,得到了比較一致的結(jié)果,驗(yàn)證了程序的正確性。接著在此基礎(chǔ)上研究了橫向剪切和縱向剪切引起的混合對(duì)流問題。發(fā)現(xiàn)橫向剪切力引起的混合對(duì)流和縱向剪切力引起的混合在流動(dòng)與傳熱特征上具有較大的差異。生物磁流體作為近年來(lái)比較熱門的復(fù)雜流體之一,引起了眾多學(xué)者的關(guān)注。在非等溫和非均勻磁場(chǎng)作用下,生物磁流體受到開爾文力和洛倫茨力以及浮升力三者的共同影響,其動(dòng)力學(xué)行為既不同于普通的鐵磁流體力學(xué)(ferrohydrodynamics,FHD),又不同于一般的磁流體力學(xué)(magnetohydrodynmics,MHD)。本文首次將DPD方法用于研究半環(huán)形區(qū)域內(nèi)的生物磁流體熱磁對(duì)流問題。研究了磁數(shù)、哈特曼數(shù)、瑞利數(shù)、普朗特?cái)?shù)對(duì)半環(huán)形區(qū)域內(nèi)溫度場(chǎng)和流場(chǎng)的影響,發(fā)現(xiàn)非均勻磁場(chǎng)下的熱磁對(duì)流呈現(xiàn)與純自然對(duì)流不同的特征。在外磁場(chǎng)下,左右兩側(cè)原來(lái)由于自然對(duì)流形成的兩個(gè)旋渦會(huì)分別分裂成兩個(gè)較小的旋渦,并且區(qū)域內(nèi)存在三個(gè)熱羽流,而純自然對(duì)流只出現(xiàn)一個(gè)熱羽流。對(duì)于受多種驅(qū)動(dòng)因素影響的流體系統(tǒng),在一定條件下,隨著驅(qū)動(dòng)力相對(duì)大小的變化,系統(tǒng)呈現(xiàn)不同的亞穩(wěn)態(tài)的結(jié)構(gòu)。DPD方法是一種有效可靠的數(shù)值方法,能夠用來(lái)求解復(fù)雜形狀內(nèi)的受多種因素影響的對(duì)流傳熱問題,幫助發(fā)現(xiàn)一些新的有趣的物理現(xiàn)象,未來(lái)在研究復(fù)雜流動(dòng)與傳熱問題時(shí)將起到重要作用。
[Abstract]:In recent years, with the emergence and high-speed development of emerging technologies, the fluid dynamics are facing the challenges of complex fluid and complex flow. in that context of a new technology, the flow of complex fluid may be caused by a multi-physical field, a physical effect, a chemical effect, or even a biological effect, may be a factor in the flow of the drive fluid, The various driving forces and their non-linear coupling make the flow problems and the heat transfer problems associated with the flow to be complex, diverse and non-linear, so the micro-structure and the transmission process of the flow need to be analyzed in-depth. As a Lagrangian particle method, the energy-conservation dissipative particle dynamics (e DPD) has a great potential for complex fluid flow and heat transfer problems with a plurality of driving forces, And the development is relatively slow, it can be said to be in the ascendant, there is still a lot of open space. In this paper, the dissipation particle dynamics method is used to study the flow and heat transfer phenomena of various driving force coupling. First, this paper systematically describes the theoretical basis of the e DPD method applied to the simulation of flow and heat transfer phenomena. The law of mass conservation, the law of conservation of momentum and the law of energy conservation of the e DPD fluid system are obtained by using the dynamic theory. In addition, the related details of dissipative particle dynamics simulation are described in detail in this paper, including boundary treatment, integral method and parameter selection. First, a feasible scheme is proposed to establish the relationship between the mesoscopic parameter and the macro transport coefficient of the dissipative particle dynamics method. According to the scheme, the problems of the flow of the shearing force and the floating-lift force and the natural convection in the simple square cavity are simulated, and the results are in good agreement with the results of the analysis and the finite volume method. The shear force is an important measure to strengthen the heat transfer in the engineering application, so the mixed convection problem caused by the shearing force and the uplift force is of great interest to the scholars. The mixed convection in the simple square cavity has been studied in detail. However, it is necessary to consider the complex shape in the engineering. In this paper, the kinetic method of the dissipative particle is applied to the problem of flow and heat transfer of simple fluid, which is caused by the shearing force and the uplift force in the isothermal enclosure of the built-in elliptical heat source. The simulation results are compared with other methods, such as the finite volume method (FVM), the lattice Boltzmann method (LBM) and the differential quadrature method (DQM). the result of the comparison is obtained, and the correctness of the program is verified. Then, the mixed convection problem caused by transverse shear and longitudinal shear is studied. It was found that the mixed convection and the longitudinal shear induced by the transverse shear forces have a great difference in the flow and heat transfer characteristics. As one of the most popular complex fluids in recent years, the bio-magnetic fluid has attracted many scholars' attention. Under the action of non-uniform and non-uniform magnetic field, the biological magnetic fluid is influenced by the Kelvin force and the Lorentz force and the uplift force, and the dynamic behavior of the magnetic fluid is different from that of the general ferrofluid dynamics (FHD), and is different from the general magnetic fluid dynamics (MHD). In this paper, the DPD method is used to study the thermal and magnetic convection of the bio-magnetic fluid in the semi-circular region. The effects of the number of magnetic numbers, the number of Hartmann, the number of Rayleigh and the Planck number on the temperature field and the flow field in the semi-annular region are studied, and the characteristics of the thermal and magnetic convection under the non-uniform magnetic field are found to be different from the pure natural convection. In the outer magnetic field, the two vortices, which are formed by natural convection, are split into two smaller vortices, respectively, and there are three hot-plume flows in the region, while the pure natural convection only occurs with one plume. For fluid systems affected by various driving factors, under certain conditions, with the change of the relative size of the driving force, the system presents different metastable structures. The DPD method is an effective and reliable numerical method, which can be used to solve the convection heat problem which is influenced by various factors in complex shape, and help to find some new and interesting physical phenomena, and will play an important role in the study of complex flow and heat transfer problems in the future.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TK124

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 劉謀斌;常建忠;;耗散粒子動(dòng)力學(xué)處理復(fù)雜固體壁面的一種有效方法[J];物理學(xué)報(bào);2010年11期

，

本文編號(hào)：2354992