剪切增稠幂律流体中单气泡上升动力学行为的格子Boltzmann方法研究  

Lattice Boltzmann method for studying dynamics of single rising bubble in shear-thickening power-law fluids

作　　者：许鑫萌 娄钦[1] Xu Xin-Meng;Lou Qin(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China)

机构地区：[1]上海理工大学能源与动力工程学院,上海200093

出　　处：《物理学报》2024年第13期190-200,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:52376068,51976128);上海浦江人才(批准号:22PJD047)资助的课题。

摘　　要：采用不可压非牛顿气液两相流格子Boltzmann方法研究了剪切增稠流体中气泡上升的动力学行为,重点分析了流变指数n、Eoυos数(Eo)和Galilei数(Ga)对气泡形变、终端速度和剪切速率的影响.数值结果表明:气泡形变程度随Eo的增大而增大,n对气泡形状的影响与Ga相关.另一方面,随着Ga增大,气泡终端速度随n呈非线性单调增大,且n对终端速度的影响随Ga的增大逐渐明显;当Ga固定且值较小时,气泡终端速度在较小Eo下随n的增大先增大后减小,而当Eo较大时终端速度随n的增大呈增大趋势;当Ga固定且较大时,气泡终端速度在Eo较大时较为统一地随n增大而增大.此外,气泡左右两端存在剪切速率较高的区域,该区域尺寸随Eo,Ga的增大而增大,随n的增大先增大后缩小.最后利用正交试验法得到上述三变量对剪切速率和终端速度的影响程度.对于剪切速率,参数影响程度由大到小的顺序依次为n,Ga和Eo;对于终端速度,Ga对其影响最大,n次之,Eo影响程度最小.Bubble motion in non-Newtonian fluids is widely present in various industrial processes such as crude oil extraction,enhancement of boiling heat transfer,CO_2 sequestration and wastewater treatment.System containing non-Newtonian liquid,as opposed to Newtonian liquid,has shear-dependent viscosity,which can change the hydrodynamic characteristics of the bubbles,such as their size,deformation,instability,terminal velocity,and shear rate,and ultimately affect the bubble rising behaviors.In this work,the dynamic behavior of bubble rising in a shear-thickened fluid is studied by using an incompressible lattice Boltzmann non-Newtonian gas-liquid two-phase flow model.The effects of the rheological exponent n,the Eotvos number(Eo),and the Galilei number(Ga)on the bubble deformation,terminal velocity,and the shear rate are investigated.The numerical results show that the degree of bubble deformation increases as Eo grows,and the effect of n on bubble deformation degree relates to Ga.On the other hand,the terminal velocity of the bubbles increases monotonically and nonlinearly with Ga for given Eo and n,and the effect of n on the terminal velocity of the bubbles turns stronger as Ga increases.When Ga is fixed and small,the terminal velocity of the bubble increases and then decreases with the increase of n at small Eo,and increases with the increase of n when Eo is large;but when Ga is fixed and large,the terminal velocity of the bubbles increases with the increase of n in a more uniform manner.In addition,regions with high shear rates can be found near the left end and right end of the bubble.The size of these regions grows with Eo and Ga,exhibiting an initial increase followed by a decrease as n increases.Finally,the orthogonal experimental method is used to obtain the influences of the aforementioned three factors on the shear rate and terminal velocity.The order of influence on shear rate is n,Ga and Eo which are arranged in descending order.For the terminal velocity,Ga has the greatest influence,followed by n,and Eo ha

关 键 词：格子BOLTZMANN方法 气泡动力学 剪切增稠流体 

分 类 号：O35[理学—流体力学]