發(fā)布時(shí)間：2018-05-22 16:42

  本文選題：懸浮粒子流 + 格子Boltzmann　； 參考：《華中科技大學(xué)》2015年碩士論文

【摘要】：顆粒-流體系統(tǒng)廣泛存在于環(huán)境工程、生命科學(xué)以及工業(yè)應(yīng)用等領(lǐng)域,其中對(duì)于懸浮顆粒運(yùn)動(dòng)規(guī)律,尤其是顆粒群的運(yùn)動(dòng)規(guī)律是多相流領(lǐng)域的一個(gè)熱點(diǎn)難點(diǎn)問(wèn)題。本文采用格子Boltzmann方法(LB)+附件邊界應(yīng)力方法(EBF)+MPI并行程序來(lái)模擬懸浮顆粒(群)的運(yùn)動(dòng)規(guī)律,顆粒的運(yùn)動(dòng)由牛頓運(yùn)動(dòng)方程進(jìn)行描述,顆粒與顆粒顆粒之間的碰撞采用Glowinski等人2001年提出的碰撞模型進(jìn)行處理。本文主要研究的是三維單、雙顆粒以及顆粒群的運(yùn)動(dòng)規(guī)律及背后存在的機(jī)理。首先,本文模擬了壁面邊界條件下不同初始位置對(duì)顆粒運(yùn)動(dòng)的影響以及不同周期邊界條件對(duì)顆粒運(yùn)動(dòng)的影響。在壁面邊界條件下,單顆粒位于不同初始位置時(shí)雖然起初會(huì)對(duì)速度有微弱影響,但并不影響其最終沉降速度;初始位置處于非中心位置時(shí),顆粒會(huì)產(chǎn)生旋轉(zhuǎn)運(yùn)動(dòng)。對(duì)于不同邊界條件下單顆粒的運(yùn)動(dòng)進(jìn)行研究,我們發(fā)現(xiàn)單顆粒在自由邊界條件下沉降的最快,其次是周期邊界,最后是壁面邊界。其次,本文詳細(xì)分析了等粒徑顆粒和非等粒徑顆粒的運(yùn)動(dòng)規(guī)律,在非等粒徑顆粒的研究中我們發(fā)現(xiàn)小顆粒在上時(shí)出現(xiàn)了多個(gè)臨界值,包括粒徑比、初始間距、密度比,這些臨界值將顆粒運(yùn)動(dòng)分成兩個(gè)區(qū)域,一個(gè)是能發(fā)生DKT現(xiàn)象的區(qū)域,另一個(gè)則是不能發(fā)生DKT現(xiàn)象的區(qū)域,而能不能發(fā)生DKT現(xiàn)象的關(guān)鍵在于不同參數(shù)下顆粒尾渦的吸引能不能導(dǎo)致后面顆粒在一定時(shí)間間距內(nèi)趕上前面顆粒。最后,本文對(duì)顆粒群運(yùn)動(dòng)進(jìn)行了模擬研究,包括不同初始位置對(duì)顆粒群運(yùn)動(dòng)的影響以及100數(shù)量級(jí)和1000數(shù)量級(jí)顆粒群的模擬,通過(guò)對(duì)速度及其統(tǒng)計(jì)量分析、位置及其統(tǒng)計(jì)量分析、顆粒流體相互作用分析使得我們對(duì)于顆粒群整體運(yùn)動(dòng)規(guī)律和機(jī)理有了一定的認(rèn)識(shí)。另外本文針對(duì)顆粒群系統(tǒng)的Ga和體積分?jǐn)?shù)進(jìn)行了研究,Ga較小時(shí)顆粒豎直沉降平均Re的震蕩微弱,Ga較大時(shí),顆粒豎直沉降平均Re的震蕩強(qiáng)烈,顆粒-流體及顆粒-顆粒間的相互作用明顯,流場(chǎng)渦量值較大,渦結(jié)構(gòu)由平滑到皺褶再到破碎、脫落。
[Abstract]:Particle fluid systems are widely used in environmental engineering, life sciences and industrial applications. Among them, the motion law of suspended particles, especially the motion of particle groups, is a hot and difficult problem in the field of multiphase flow. In this paper, the lattice Boltzmann method is used to simulate the motion of suspended particles (groups) by using the adnexal boundary stress method (EBF) MPI. The motion of particles is described by Newtonian equation of motion. The collision between particles is treated by the collision model proposed by Glowinski et al in 2001. In this paper, the motion and mechanism of three dimensional single, double particles and particle groups are studied. Firstly, the effects of different initial positions on particle motion and the effects of different periodic boundary conditions on particle motion under the wall boundary condition are simulated. Under the condition of wall boundary, single particle at different initial position will have weak influence on velocity at first, but it will not affect the final settlement velocity, and when the initial position is in non-central position, the particle will produce rotational motion. For the study of the movement of the ordered particles under different boundary conditions, we find that the settlement of single particles is the fastest under the free boundary condition, followed by the periodic boundary, and finally the wall boundary. Secondly, in this paper, we analyze the movement law of equal and non-equal size particles in detail. In the study of non-equal particle size, we find that there are several critical values when small particles are up, including particle size ratio, initial spacing, density ratio. These critical values divide the motion of particles into two regions, one where the DKT phenomenon can occur, and the other where the DKT phenomenon cannot occur. The key to the occurrence of DKT phenomenon lies in the attraction energy of particle wake under different parameters, whether the latter particles catch up with the front particles within a certain time interval. Finally, the motion of particle group is simulated, including the influence of different initial position on particle group motion, and the simulation of 100th and 1000 order of magnitude particle group. Through the analysis of velocity and its statistics, the position and its statistics are analyzed. The analysis of particle-fluid interaction gives us a certain understanding of the law and mechanism of particle group motion. In addition, for the Ga and volume fraction of the particle group system, it is studied that when the oscillation of the average re of the vertical sedimentation of particles is weak and Ga is large, the oscillation of the average re of the vertical sedimentation of the particles is strong. The interaction between particle and fluid and between particle and particle is obvious, the vorticity of flow field is larger, and the vortex structure changes from smoothness to wrinkle to breakage and shedding.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O347.7;O241

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前4條

1 王亮;基于格子Boltzmann方法的非常規(guī)顆粒兩相流的機(jī)理研究[D];華中科技大學(xué);2012年

2 何冰;基于Boltzmann方程三維可壓縮高速流動(dòng)并行算法及其應(yīng)用研究[D];上海大學(xué);2008年

3 段雅麗;格子Boltzmann方法及其在流體動(dòng)力學(xué)上的一些應(yīng)用[D];中國(guó)科學(xué)技術(shù)大學(xué);2007年

4 陳勝;格子Boltzmann方法模擬多相（反應(yīng)）流動(dòng)[D];華中科技大學(xué);2005年

相關(guān)碩士學(xué)位論文 前4條

1 包勝;圓柱繞流與顆粒懸浮流動(dòng)的格子Boltzmann模擬[D];華中科技大學(xué);2012年

2 李瑞霞;均勻湍流內(nèi)湍流—布朗顆粒碰撞的直接模擬研究[D];華中科技大學(xué);2006年

3 李小寶;格子BOLTZMANN方法及其在柱體繞流數(shù)值模擬中的應(yīng)用[D];天津大學(xué);2006年

4 韓海鋒;格子Boltzmann方法并行算法設(shè)計(jì)與數(shù)值模擬[D];華中科技大學(xué);2004年

，

本文編號(hào)：1922845